diff --git a/README.md b/README.md
index 0ff9cad..16fff83 100644
--- a/README.md
+++ b/README.md
@@ -77,7 +77,7 @@ Example `.env` variables (or export in shell):
 ```
 MAILTRAP_API_KEY=your_api_token # https://mailtrap.io/api-tokens
 MAILTRAP_USE_SANDBOX=true       # true/false toggle
-MAILTRAP_INBOX_ID=123456        # Only needed for sandbox
+MAILTRAP_SANDBOX_ID=123456      # Only needed for sandbox
 ```
 
 Bootstrap logic:
@@ -93,12 +93,12 @@ require __DIR__ . '/vendor/autoload.php';
 
 $apiKey    = getenv('MAILTRAP_API_KEY');
 $isSandbox = filter_var(getenv('MAILTRAP_USE_SANDBOX'), FILTER_VALIDATE_BOOL);
-$inboxId   = $isSandbox ? getenv('MAILTRAP_INBOX_ID') : null; // required only for sandbox
+$sandboxId = $isSandbox ? getenv('MAILTRAP_SANDBOX_ID') : null; // required only for sandbox
 
 $client = MailtrapClient::initSendingEmails(
     apiKey: $apiKey,
     isSandbox: $isSandbox,
-    inboxId: $inboxId // null is ignored for production
+    sandboxId: $sandboxId // null is ignored for production
 );
 
 $email = (new MailtrapEmail())
@@ -142,7 +142,7 @@ $mailtrap = MailtrapClient::initSendingEmails(
     apiKey: getenv('MAILTRAP_API_KEY'), # your API token
     isBulk: false,                      # set to true for bulk email sending (false by default)
     isSandbox: false,                   # set to true for sandbox mode       (false by default)
-    inboxId: null                       # optional, only for sandbox mode    (false by default)
+    sandboxId: null                     # required only for sandbox mode     (null by default)
 );
 
 $email = (new MailtrapEmail())
@@ -239,21 +239,21 @@ Email API:
 - Batch send (Bulk) – [`batch/bulk.php`](examples/batch/bulk.php)
 - Batch send with Template (Transactional) – [`batch/transactional_template.php`](examples/batch/transactional_template.php)
 - Batch send with Template (Bulk) – [`batch/bulk_template.php`](examples/batch/bulk_template.php)
-- Sending domain management CRUD – [`sending-domains/all.php`](examples/sending-domains/all.php)
-- Sending domain company info – [`sending-domains/company-info.php`](examples/sending-domains/company-info.php)
+- Domain management CRUD – [`domains/all.php`](examples/domains/all.php)
+- Domain company info – [`domains/company-info.php`](examples/domains/company-info.php)
 - Suppressions (create, find & delete) – [`sending/suppressions.php`](examples/sending/suppressions.php)
 - Tracking Opt-outs (list, create & delete) – [`sending/tracking-opt-outs.php`](examples/sending/tracking-opt-outs.php)
 - Email Logs (list & get by message ID) – [`sending/email-logs.php`](examples/sending/email-logs.php)
 
-Email Sandbox (Testing):
-- Send an email (Sandbox) – [`testing/send-mail.php`](examples/testing/send-mail.php)
-- Send an email with a Template (Sandbox) – [`testing/template.php`](examples/testing/template.php)
+Email Sandbox:
+- Send an email (Sandbox) – [`sandbox/send-mail.php`](examples/sandbox/send-mail.php)
+- Send an email with a Template (Sandbox) – [`sandbox/template.php`](examples/sandbox/template.php)
 - Batch send (Sandbox) – [`batch/sandbox.php`](examples/batch/sandbox.php)
 - Batch send with Template (Sandbox) – [`batch/sandbox_template.php`](examples/batch/sandbox_template.php)
-- Message management CRUD – [`testing/messages.php`](examples/testing/messages.php)
-- Inbox management CRUD – [`testing/inboxes.php`](examples/testing/inboxes.php)
-- Project management CRUD – [`testing/projects.php`](examples/testing/projects.php)
-- Attachments operations – [`testing/attachments.php`](examples/testing/attachments.php)
+- Message management CRUD – [`sandbox/messages.php`](examples/sandbox/messages.php)
+- Sandbox management CRUD – [`sandbox/sandboxes.php`](examples/sandbox/sandboxes.php)
+- Project management CRUD – [`sandbox/projects.php`](examples/sandbox/projects.php)
+- Attachments operations – [`sandbox/attachments.php`](examples/sandbox/attachments.php)
 
 Inbound Email API:
 - Folder management CRUD – [`inbound/folders.php`](examples/inbound/folders.php)
@@ -297,6 +297,31 @@ See the full indexed list at [`examples/README.md`](examples/README.md).
 Webhooks:
 - Verifying webhook signatures – [`webhooks/verify_signature.php`](examples/webhooks/verify_signature.php)
 
+## Renamed APIs
+
+The Email Sandbox's testing inboxes are now called **sandboxes**, and sending domains are now called **domains**.
+The SDK follows these names. The old ones still work: they call the same API endpoints, and each emits an
+`E_USER_DEPRECATED` notice the first time it is used. Symfony and Laravel log these notices; plain PHP ignores them.
+The old names will be removed in a future major release.
+
+| Old name (deprecated) | New name |
+|---|---|
+| `MailtrapSandboxClient::inboxes($accountId)` | `MailtrapSandboxClient::sandboxes($accountId)` |
+| `Mailtrap\Api\Sandbox\Inbox` | `Mailtrap\Api\Sandbox\Sandbox` |
+| `Inbox::getInboxAttributes($inboxId)` | `Sandbox::getSandboxAttributes($sandboxId)` |
+| `Mailtrap\DTO\Request\Inbox` | `Mailtrap\DTO\Request\Sandbox` |
+| `inboxId:` argument of `MailtrapClient::initSendingEmails()` and of the sandbox `emails()`, `messages()` and `attachments()` | `sandboxId:` |
+| `getInboxId()` of the sandbox `Emails`, `Message` and `Attachment` APIs | `getSandboxId()` |
+| Symfony DSN option `?inboxId=` | `?sandboxId=` |
+| Laravel `services.mailtrap-sdk.inboxId` config key | `services.mailtrap-sdk.sandboxId` (`MAILTRAP_SANDBOX_ID`) |
+| `Domain::getSendingDomains()` | `Domain::getDomains()` |
+| `Domain::createSendingDomain($domainName)` | `Domain::createDomain($domainName)` |
+| `Domain::updateSendingDomain($domainId, $domain)` | `Domain::updateDomain($domainId, $domain)` |
+| `Domain::deleteSendingDomain($domainId)` | `Domain::deleteDomain($domainId)` |
+
+Names that mirror an API field keep the old term, for example `inbox_id` in message responses,
+`User::getList($inboxIds)`, `PermissionInterface::TYPE_INBOX` and the `sendingDomainIds` stats filters.
+
 ## Contributing
 
 Bug reports and pull requests are welcome on [GitHub](https://github.com/railsware/mailtrap-php). This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](CODE_OF_CONDUCT.md).
diff --git a/UPGRADE-2.0.md b/UPGRADE-2.0.md
index 8483f9d..9f7ba16 100644
--- a/UPGRADE-2.0.md
+++ b/UPGRADE-2.0.md
@@ -68,7 +68,7 @@ UPGRADE FROM 1.x to 2.0
   ```
 
 ### Sandbox API
-* **BC BREAK**: Rebuild `Projects` & `Messages` & `Attachments` & `Inboxes` layers ([examples](examples/testing))
+* **BC BREAK**: Rebuild `Projects` & `Messages` & `Attachments` & `Inboxes` layers ([examples](examples/sandbox))
 
   __Before__:
   ```php
diff --git a/examples/README.md b/examples/README.md
index 084516e..1633c50 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -3,8 +3,8 @@
 Central index of runnable example scripts demonstrating Mailtrap PHP SDK features. Each script is intentionally minimal; open the file to inspect parameters. Run examples from project root (adjust env vars first).
 
 ## Prerequisites
-* Export or place inside the file your ENV variables (MAILTRAP_API_KEY, MAILTRAP_INBOX_ID, etc)
-* Some examples require a verified sending domain (production / bulk / templates).
+* Export or place inside the file your ENV variables (MAILTRAP_API_KEY, MAILTRAP_SANDBOX_ID, etc)
+* Some examples require a verified domain (production / bulk / templates).
 
 ## Contents
 
@@ -31,16 +31,16 @@ Central index of runnable example scripts demonstrating Mailtrap PHP SDK feature
 | Sandbox batch send | [`batch/sandbox.php`](batch/sandbox.php) |
 | Sandbox batch send (template) | [`batch/sandbox_template.php`](batch/sandbox_template.php) |
 
-### Sandbox (Email Testing)
+### Email Sandbox
 
 | Purpose | File |
 |---------|------|
-| Sandbox transactional send | [`testing/send-mail.php`](testing/send-mail.php) |
-| Sandbox send with template | [`testing/template.php`](testing/template.php) |
-| Manage attachments of a message | [`testing/attachments.php`](testing/attachments.php) |
-| Inbox CRUD / listing | [`testing/inboxes.php`](testing/inboxes.php) |
-| Message CRUD / listing | [`testing/messages.php`](testing/messages.php) |
-| Project CRUD / listing | [`testing/projects.php`](testing/projects.php) |
+| Sandbox transactional send | [`sandbox/send-mail.php`](sandbox/send-mail.php) |
+| Sandbox send with template | [`sandbox/template.php`](sandbox/template.php) |
+| Manage attachments of a message | [`sandbox/attachments.php`](sandbox/attachments.php) |
+| Sandbox CRUD / listing | [`sandbox/sandboxes.php`](sandbox/sandboxes.php) |
+| Message CRUD / listing | [`sandbox/messages.php`](sandbox/messages.php) |
+| Project CRUD / listing | [`sandbox/projects.php`](sandbox/projects.php) |
 
 ### Inbound Email
 
@@ -68,8 +68,8 @@ Central index of runnable example scripts demonstrating Mailtrap PHP SDK feature
 |---------|------|
 | Templates CRUD + paginated list (experimental) | [`templates/templates.php`](templates/templates.php) |
 | Email templates CRUD | [`templates/all.php`](templates/all.php) |
-| Sending domains CRUD | [`sending-domains/all.php`](sending-domains/all.php) |
-| Sending domain company info | [`sending-domains/company-info.php`](sending-domains/company-info.php) |
+| Domains CRUD | [`domains/all.php`](domains/all.php) |
+| Domain company info | [`domains/company-info.php`](domains/company-info.php) |
 
 ### General API
 
@@ -104,6 +104,6 @@ For batch examples, ensure the stream (bulk vs transactional vs sandbox) matches
 ## Tips
 - Keep secrets out of committed files; rely on environment variables.
 - Template examples require existing template UUIDs in your Mailtrap account.
-- Sandbox examples need `MAILTRAP_INBOX_ID`.
+- Sandbox examples need `MAILTRAP_SANDBOX_ID`.
 
 ---
diff --git a/examples/batch/bulk.php b/examples/batch/bulk.php
index 188479b..dc92303 100644
--- a/examples/batch/bulk.php
+++ b/examples/batch/bulk.php
@@ -16,7 +16,7 @@
  * Users of this endpoint should check the success and errors for each message in the response (the results are ordered the same as the original messages - requests).
  * Please note that the endpoint accepts up to 500 messages per API call, and up to 50 MB payload size, including attachments.
  *
- * For this example, you need to have ready-to-use sending domain or, a Demo domain that allows sending emails to your own account email.
+ * For this example, you need to have ready-to-use domain or, a Demo domain that allows sending emails to your own account email.
  * @see https://help.mailtrap.io/article/69-sending-domain-setup
  */
 try {
diff --git a/examples/batch/bulk_template.php b/examples/batch/bulk_template.php
index ff851de..4cf74c9 100644
--- a/examples/batch/bulk_template.php
+++ b/examples/batch/bulk_template.php
@@ -15,7 +15,7 @@
  * UUID of email template. Subject, text and html will be generated from template using optional template_variables.
  * Optional template variables that will be used to generate actual subject, text and html from email template
  *
- * For this example, you need to have ready-to-use sending domain or, a Demo domain that allows sending emails to your own account email.
+ * For this example, you need to have ready-to-use domain or, a Demo domain that allows sending emails to your own account email.
  * @see https://help.mailtrap.io/article/69-sending-domain-setup
  */
 try {
diff --git a/examples/batch/sandbox.php b/examples/batch/sandbox.php
index 133a0e9..c1e5c6b 100644
--- a/examples/batch/sandbox.php
+++ b/examples/batch/sandbox.php
@@ -19,7 +19,7 @@
     $mailtrap = MailtrapClient::initSendingEmails(
         apiKey: $_ENV['MAILTRAP_API_KEY'], #your API token from here https://mailtrap.io/api-tokens
         isSandbox: true, # Sandbox sending (@see https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing)
-        inboxId: $_ENV['MAILTRAP_INBOX_ID'] # required param for sandbox sending
+        sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'] # required param for sandbox sending
     );
 
     $baseEmail = (new MailtrapEmail())
diff --git a/examples/batch/sandbox_template.php b/examples/batch/sandbox_template.php
index 329629b..5e462e3 100644
--- a/examples/batch/sandbox_template.php
+++ b/examples/batch/sandbox_template.php
@@ -19,7 +19,7 @@
     $mailtrap = MailtrapClient::initSendingEmails(
         apiKey: $_ENV['MAILTRAP_API_KEY'], #your API token from here https://mailtrap.io/api-tokens
         isSandbox: true, # Sandbox sending (@see https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing)
-        inboxId: $_ENV['MAILTRAP_INBOX_ID'] # required param for sandbox sending
+        sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'] # required param for sandbox sending
     );
 
     $baseEmail = (new MailtrapEmail())
diff --git a/examples/batch/transactional.php b/examples/batch/transactional.php
index 028448f..39d470c 100644
--- a/examples/batch/transactional.php
+++ b/examples/batch/transactional.php
@@ -16,7 +16,7 @@
  * Users of this endpoint should check the success and errors for each message in the response (the results are ordered the same as the original messages - requests).
  * Please note that the endpoint accepts up to 500 messages per API call, and up to 50 MB payload size, including attachments.
  *
- * For this example, you need to have ready-to-use sending domain or, a Demo domain that allows sending emails to your own account email.
+ * For this example, you need to have ready-to-use domain or, a Demo domain that allows sending emails to your own account email.
  * @see https://help.mailtrap.io/article/69-sending-domain-setup
  */
 try {
diff --git a/examples/batch/transactional_template.php b/examples/batch/transactional_template.php
index 83c646e..629cfaa 100644
--- a/examples/batch/transactional_template.php
+++ b/examples/batch/transactional_template.php
@@ -15,7 +15,7 @@
  * UUID of email template. Subject, text and html will be generated from template using optional template_variables.
  * Optional template variables that will be used to generate actual subject, text and html from email template
  *
- * For this example, you need to have ready-to-use sending domain or, a Demo domain that allows sending emails to your own account email.
+ * For this example, you need to have ready-to-use domain or, a Demo domain that allows sending emails to your own account email.
  * @see https://help.mailtrap.io/article/69-sending-domain-setup
  */
 try {
diff --git a/examples/sending-domains/all.php b/examples/domains/all.php
similarity index 80%
rename from examples/sending-domains/all.php
rename to examples/domains/all.php
index 415a1e7..47ed3bf 100644
--- a/examples/sending-domains/all.php
+++ b/examples/domains/all.php
@@ -12,15 +12,15 @@
 $accountId = (int) $_ENV['MAILTRAP_ACCOUNT_ID'];
 $config = new Config($_ENV['MAILTRAP_API_KEY']); #your API token from here https://mailtrap.io/api-tokens
 
-$sendingDomains = (new MailtrapSendingClient($config))->domains($accountId); #required parameter is accountId
+$domains = (new MailtrapSendingClient($config))->domains($accountId); #required parameter is accountId
 
 /**
- * Get a list of sending domains.
+ * Get a list of domains.
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/domains
  */
 try {
-    $response = $sendingDomains->getSendingDomains();
+    $response = $domains->getDomains();
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -30,14 +30,14 @@
 
 
 /**
- * Create a new sending domain
+ * Create a new domain
  *
  * POST https://mailtrap.io/api/accounts/{account_id}/domains
  */
 try {
     $domainName = 'example.com';
 
-    $response = $sendingDomains->createSendingDomain($domainName);
+    $response = $domains->createDomain($domainName);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -47,14 +47,14 @@
 
 
 /**
- * Get a sending domain by ID
+ * Get a domain by ID
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/domains/{domain_id}
  */
 try {
     $domainId = (int) $_ENV['MAILTRAP_DOMAIN_ID']; // Set this environment variable with a valid domain ID
 
-    $response = $sendingDomains->getDomainById($domainId);
+    $response = $domains->getDomainById($domainId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -72,7 +72,7 @@
     $domainId = (int) $_ENV['MAILTRAP_DOMAIN_ID']; // Set this environment variable with a valid domain ID
     $email = 'devops@example.com'; // Email address to send setup instructions to
 
-    $response = $sendingDomains->sendDomainSetupInstructions($domainId, $email);
+    $response = $domains->sendDomainSetupInstructions($domainId, $email);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -82,14 +82,14 @@
 
 
 /**
- * Update sending domain configuration settings
+ * Update domain configuration settings
  *
  * PATCH https://mailtrap.io/api/accounts/{account_id}/domains/{domain_id}
  */
 try {
     $domainId = (int) $_ENV['MAILTRAP_DOMAIN_ID']; // Set this environment variable with a valid domain ID
 
-    $response = $sendingDomains->updateSendingDomain(
+    $response = $domains->updateDomain(
         $domainId,
         new UpdateDomain(
             openTrackingEnabled: true,
@@ -108,14 +108,14 @@
 
 
 /**
- * Delete a sending domain
+ * Delete a domain
  *
  * DELETE https://mailtrap.io/api/accounts/{account_id}/domains/{domain_id}
  */
 try {
     $domainId = (int) $_ENV['MAILTRAP_DOMAIN_ID']; // Set this environment variable with a valid domain ID
 
-    $response = $sendingDomains->deleteSendingDomain($domainId);
+    $response = $domains->deleteDomain($domainId);
 
     // Print the response status code
     var_dump($response->getStatusCode());
diff --git a/examples/sending-domains/company-info.php b/examples/domains/company-info.php
similarity index 94%
rename from examples/sending-domains/company-info.php
rename to examples/domains/company-info.php
index 045310b..818d68f 100644
--- a/examples/sending-domains/company-info.php
+++ b/examples/domains/company-info.php
@@ -17,7 +17,7 @@
 $companyInfo = (new MailtrapSendingClient($config))->companyInfo($domainId); #required parameter is domainId
 
 /**
- * Create company info for a sending domain
+ * Create company info for a domain
  *
  * POST https://mailtrap.io/api/domains/{domain_id}/company_info
  */
@@ -45,7 +45,7 @@
 
 
 /**
- * Get company info for a sending domain
+ * Get company info for a domain
  *
  * GET https://mailtrap.io/api/domains/{domain_id}/company_info
  */
@@ -60,7 +60,7 @@
 
 
 /**
- * Update company info for a sending domain
+ * Update company info for a domain
  *
  * PATCH https://mailtrap.io/api/domains/{domain_id}/company_info
  *
diff --git a/examples/email-campaigns/all.php b/examples/email-campaigns/all.php
index 9aa94f6..f89178d 100644
--- a/examples/email-campaigns/all.php
+++ b/examples/email-campaigns/all.php
@@ -42,7 +42,7 @@
 try {
     $response = $emailCampaigns->createEmailCampaign(new CreateEmailCampaign(
         name: 'Spring Sale',
-        domainId: (int) $_ENV['MAILTRAP_DOMAIN_ID'], // set this environment variable with your sending domain ID
+        domainId: (int) $_ENV['MAILTRAP_DOMAIN_ID'], // set this environment variable with your domain ID
         fromLocalPart: 'news',
         templateAttributes: new TemplateAttributes(subject: 'Spring is here — 30% off'),
         fromDisplayName: 'Acme Marketing',
diff --git a/examples/general/billing.php b/examples/general/billing.php
index 4180ac6..8e73134 100644
--- a/examples/general/billing.php
+++ b/examples/general/billing.php
@@ -12,7 +12,7 @@
 
 
 /**
- * Get current billing cycle usage for Email Testing and Email Sending.
+ * Get current billing cycle usage for Email Sandbox and Email Sending.
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/billing/usage
  */
diff --git a/examples/laravel/sandbox.php b/examples/laravel/sandbox.php
index 2465dd2..5b8ade2 100644
--- a/examples/laravel/sandbox.php
+++ b/examples/laravel/sandbox.php
@@ -19,7 +19,7 @@
     $response = MailtrapClient::initSendingEmails(
         apiKey:    $_ENV['MAILTRAP_API_KEY'], // your API token from here https://mailtrap.io/api-tokens
         isSandbox: true,
-        inboxId:   $_ENV['MAILTRAP_INBOX_ID'], // your Inbox ID from here https://mailtrap.io/inboxes
+        sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'], // your Sandbox ID from here https://mailtrap.io/inboxes
     )->send($email);
 
     var_dump(ResponseHelper::toArray($response));
diff --git a/examples/marketing-stats/all.php b/examples/marketing-stats/all.php
index 588d6a3..aed2945 100644
--- a/examples/marketing-stats/all.php
+++ b/examples/marketing-stats/all.php
@@ -38,7 +38,7 @@
 
 /**
  * Get Email Marketing stats with filters: campaigns only, sent to Google and Yahoo.
- * Pass `sendingDomainIds` as well to narrow the stats to specific sending domains.
+ * Pass `sendingDomainIds` as well to narrow the stats to specific domains.
  *
  * GET https://mailtrap.io/api/marketing/stats
  */
diff --git a/examples/testing/attachments.php b/examples/sandbox/attachments.php
similarity index 91%
rename from examples/testing/attachments.php
rename to examples/sandbox/attachments.php
index 1a10c74..d3b6d54 100644
--- a/examples/testing/attachments.php
+++ b/examples/sandbox/attachments.php
@@ -7,10 +7,10 @@
 require __DIR__ . '/../../vendor/autoload.php';
 
 $accountId = $_ENV['MAILTRAP_ACCOUNT_ID'];
-$inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+$sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 $config = new Config($_ENV['MAILTRAP_API_KEY']); #your API token from here https://mailtrap.io/api-tokens
 
-$sandboxAttachments = (new MailtrapSandboxClient($config))->attachments($accountId, $inboxId); #required parameters are accountId amd inboxId
+$sandboxAttachments = (new MailtrapSandboxClient($config))->attachments($accountId, $sandboxId); #required parameters are accountId and sandboxId
 
 
 /**
diff --git a/examples/testing/messages.php b/examples/sandbox/messages.php
similarity index 87%
rename from examples/testing/messages.php
rename to examples/sandbox/messages.php
index b9301e5..a6d6355 100644
--- a/examples/testing/messages.php
+++ b/examples/sandbox/messages.php
@@ -8,10 +8,10 @@
 
 // your API token from here https://mailtrap.io/api-tokens
 $accountId = $_ENV['MAILTRAP_ACCOUNT_ID'];
-$inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+$sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 $config = new Config($_ENV['MAILTRAP_API_KEY']); #your API token from here https://mailtrap.io/api-tokens
 
-$sandboxMessages = (new MailtrapSandboxClient($config))->messages($accountId, $inboxId); #required parameters are accountId and inboxId
+$sandboxMessages = (new MailtrapSandboxClient($config))->messages($accountId, $sandboxId); #required parameters are accountId and sandboxId
 
 /**
  * Get messages
@@ -40,7 +40,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getById($messageId);
 
@@ -57,7 +57,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.htmlsource
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getSource($messageId);
 
@@ -74,7 +74,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.eml
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getEml($messageId);
 
@@ -91,7 +91,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.html
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getHtml($messageId);
 
@@ -108,7 +108,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.raw
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getRaw($messageId);
 
@@ -125,7 +125,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.txt
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getText($messageId);
 
@@ -142,7 +142,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/analyze
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getHtmlAnalysis($messageId);
 
@@ -159,7 +159,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/spam_report
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getSpamScore($messageId);
 
@@ -176,7 +176,7 @@
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->markAsRead($messageId);
 
@@ -193,7 +193,7 @@
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/mail_headers
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->getMailHeaders($messageId);
 
@@ -209,7 +209,7 @@
  * POST https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/forward
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->forward($messageId, 'recipient@example.com');
 
@@ -225,7 +225,7 @@
  * DELETE https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}
  */
 try {
-    $messageId = $_ENV['MAILTRAP_INBOX_MESSAGE_ID'];
+    $messageId = $_ENV['MAILTRAP_SANDBOX_MESSAGE_ID'];
 
     $response = $sandboxMessages->delete($messageId);
 
diff --git a/examples/testing/projects.php b/examples/sandbox/projects.php
similarity index 94%
rename from examples/testing/projects.php
rename to examples/sandbox/projects.php
index e0dea6a..f6da308 100644
--- a/examples/testing/projects.php
+++ b/examples/sandbox/projects.php
@@ -12,7 +12,7 @@
 $sandboxProjects = (new MailtrapSandboxClient($config))->projects($accountId); #required parameter is accountId
 
 /**
- * List projects and their inboxes to which the API token has access.
+ * List projects and their sandboxes to which the API token has access.
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/projects
  */
@@ -27,7 +27,7 @@
 
 
 /**
- * Get the project and its inboxes.
+ * Get the project and its sandboxes.
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/projects/{project_id}
  */
@@ -80,7 +80,7 @@
 
 
 /**
- * Delete project and its inboxes.
+ * Delete project and its sandboxes.
  *
  * DELETE https://mailtrap.io/api/accounts/{account_id}/projects/{project_id}
  */
diff --git a/examples/testing/inboxes.php b/examples/sandbox/sandboxes.php
similarity index 70%
rename from examples/testing/inboxes.php
rename to examples/sandbox/sandboxes.php
index a9cff8d..9d24695 100644
--- a/examples/testing/inboxes.php
+++ b/examples/sandbox/sandboxes.php
@@ -1,7 +1,7 @@
 <?php
 
 use Mailtrap\Config;
-use Mailtrap\DTO\Request\Inbox;
+use Mailtrap\DTO\Request\Sandbox;
 use Mailtrap\Helper\ResponseHelper;
 use Mailtrap\MailtrapSandboxClient;
 
@@ -10,15 +10,15 @@
 $accountId = $_ENV['MAILTRAP_ACCOUNT_ID'];
 $config = new Config($_ENV['MAILTRAP_API_KEY']); #your API token from here https://mailtrap.io/api-tokens
 
-$sandboxInboxes = (new MailtrapSandboxClient($config))->inboxes($accountId); #required parameter is accountId
+$sandboxes = (new MailtrapSandboxClient($config))->sandboxes($accountId); #required parameter is accountId
 
 /**
- * Get a list of inboxes.
+ * Get a list of sandboxes.
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes
  */
 try {
-    $response = $sandboxInboxes->getList();
+    $response = $sandboxes->getList();
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -28,15 +28,15 @@
 
 
 /**
- * Create an inbox
+ * Create a sandbox
  *
  * POST https://mailtrap.io/api/accounts/{account_id}/projects/{project_id}/inboxes
  */
 try {
     $projectId = $_ENV['MAILTRAP_PROJECT_ID'];
-    $inboxName = 'First inbox';
+    $sandboxName = 'First sandbox';
 
-    $response = $sandboxInboxes->create($projectId, $inboxName);
+    $response = $sandboxes->create($projectId, $sandboxName);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -46,14 +46,14 @@
 
 
 /**
- * Get inbox attributes
+ * Get sandbox attributes
  *
  * GET https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->getInboxAttributes($inboxId);
+    $response = $sandboxes->getSandboxAttributes($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -63,14 +63,14 @@
 
 
 /**
- * Delete an inbox
+ * Delete a sandbox
  *
  * DELETE https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->delete($inboxId);
+    $response = $sandboxes->delete($sandboxId);
 
     // Print the response status code
     var_dump($response->getStatusCode());
@@ -85,9 +85,9 @@
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/reset_email_username
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->resetEmailAddress($inboxId);
+    $response = $sandboxes->resetEmailAddress($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -102,9 +102,9 @@
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/toggle_email_username
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->toggleEmailAddress($inboxId);
+    $response = $sandboxes->toggleEmailAddress($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -119,9 +119,9 @@
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/reset_credentials
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->resetSmtpCredentials($inboxId);
+    $response = $sandboxes->resetSmtpCredentials($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -136,9 +136,9 @@
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/all_read
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->markAsRead($inboxId);
+    $response = $sandboxes->markAsRead($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -148,14 +148,14 @@
 
 
 /**
- * Clean inbox
+ * Clean sandbox
  *
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}/clean
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
 
-    $response = $sandboxInboxes->clean($inboxId);
+    $response = $sandboxes->clean($sandboxId);
 
     // print the response body (array)
     var_dump(ResponseHelper::toArray($response));
@@ -165,18 +165,18 @@
 
 
 /**
- * Update an inbox
+ * Update a sandbox
  *
  * PATCH https://mailtrap.io/api/accounts/{account_id}/inboxes/{inbox_id}
  */
 try {
-    $inboxId = $_ENV['MAILTRAP_INBOX_ID'];
-    $newInboxName = 'New inbox name';
+    $sandboxId = $_ENV['MAILTRAP_SANDBOX_ID'];
+    $newSandboxName = 'New sandbox name';
     $newEmailUsername = 'new-email-username';
 
-    $response = $sandboxInboxes->update(
-        $inboxId,
-        new Inbox($newInboxName, $newEmailUsername)
+    $response = $sandboxes->update(
+        $sandboxId,
+        new Sandbox($newSandboxName, $newEmailUsername)
     );
 
     // print the response body (array)
diff --git a/examples/testing/send-mail.php b/examples/sandbox/send-mail.php
similarity index 91%
rename from examples/testing/send-mail.php
rename to examples/sandbox/send-mail.php
index 5e0c1da..72a1a2f 100644
--- a/examples/testing/send-mail.php
+++ b/examples/sandbox/send-mail.php
@@ -10,7 +10,7 @@
 
 
 /**
- * Email Testing API
+ * Email Sandbox API
  *
  * POST https://sandbox.api.mailtrap.io/api/send/{inbox_id}
  */
@@ -18,7 +18,7 @@
     $mailtrap = MailtrapClient::initSendingEmails(
         apiKey: $_ENV['MAILTRAP_API_KEY'], #your API token from here https://mailtrap.io/api-tokens
         isSandbox: true, # Sandbox sending (@see https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing)
-        inboxId: $_ENV['MAILTRAP_INBOX_ID'] # required param for sandbox sending
+        sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'] # required param for sandbox sending
     );
 
     $email = (new MailtrapEmail())
diff --git a/examples/testing/template.php b/examples/sandbox/template.php
similarity index 94%
rename from examples/testing/template.php
rename to examples/sandbox/template.php
index 24a4638..edf916d 100644
--- a/examples/testing/template.php
+++ b/examples/sandbox/template.php
@@ -21,7 +21,7 @@
     $mailtrap = MailtrapClient::initSendingEmails(
         apiKey: $_ENV['MAILTRAP_API_KEY'], #your API token from here https://mailtrap.io/api-tokens
         isSandbox: true, # Sandbox sending (@see https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing)
-        inboxId: $_ENV['MAILTRAP_INBOX_ID'] # required param for sandbox sending
+        sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'] # required param for sandbox sending
     );
 
     $email = (new MailtrapEmail())
diff --git a/examples/symfony/sandbox.php b/examples/symfony/sandbox.php
index 01c0b6a..be686d5 100644
--- a/examples/symfony/sandbox.php
+++ b/examples/symfony/sandbox.php
@@ -25,7 +25,7 @@ public function __invoke(): int { // Available since Symfony 7.0. For earlier ve
         $response = MailtrapClient::initSendingEmails(
             apiKey:    $_ENV['MAILTRAP_API_KEY'], // your API token from here https://mailtrap.io/api-tokens
             isSandbox: true,
-            inboxId:   $_ENV['MAILTRAP_INBOX_ID'], // your Inbox ID from here https://mailtrap.io/inboxes
+            sandboxId: $_ENV['MAILTRAP_SANDBOX_ID'], // your Sandbox ID from here https://mailtrap.io/inboxes
         )->send($email);
 
         var_dump(ResponseHelper::toArray($response));
diff --git a/src/AbstractMailtrapClient.php b/src/AbstractMailtrapClient.php
index 84bc046..6037dd3 100644
--- a/src/AbstractMailtrapClient.php
+++ b/src/AbstractMailtrapClient.php
@@ -5,7 +5,6 @@
 namespace Mailtrap;
 
 use Mailtrap\Exception\BadMethodCallException;
-use Mailtrap\Exception\InvalidArgumentException;
 
 /**
  * Class AbstractMailtrapClient
@@ -18,11 +17,13 @@ public function __construct(protected ConfigInterface $config)
 
     public function __call(string $name, array $arguments)
     {
-        try {
-            return $this->initByName($name, $arguments);
-        } catch (InvalidArgumentException) {
+        $className = $this->getClassByName($name);
+        if (null === $className) {
             throw new BadMethodCallException(sprintf('%s -> undefined method called: "%s"', static::class, $name));
         }
+
+        /** @psalm-suppress LessSpecificReturnStatement */
+        return new $className($this->getConfig(), ...$arguments);
     }
 
     public function getConfig(): ConfigInterface
@@ -35,15 +36,4 @@ private function getClassByName(string $name): ?string
         /** @psalm-suppress UndefinedConstant */
         return !empty(static::API_MAPPING[$name]) ? static::API_MAPPING[$name] : null;
     }
-
-    private function initByName(string $name, $arguments)
-    {
-        $className = $this->getClassByName($name);
-        if (null === $className) {
-            throw new InvalidArgumentException(sprintf('%s -> undefined api instance called: "%s"', static::class, $name));
-        }
-
-        /** @psalm-suppress LessSpecificReturnStatement */
-        return new $className($this->getConfig(), ...$arguments);
-    }
 }
diff --git a/src/Api/Sandbox/Attachment.php b/src/Api/Sandbox/Attachment.php
index 574dcf7..0e88ddc 100644
--- a/src/Api/Sandbox/Attachment.php
+++ b/src/Api/Sandbox/Attachment.php
@@ -13,16 +13,23 @@
  */
 class Attachment extends AbstractApi implements SandboxInterface
 {
+    use SandboxIdTrait;
+
+    /**
+     * @param int|null $inboxId deprecated, use $sandboxId instead
+     */
     public function __construct(
         ConfigInterface $config,
         private int $accountId,
-        private int $inboxId,
+        ?int $sandboxId = null,
+        ?int $inboxId = null,
     ) {
         parent::__construct($config);
+        $this->setSandboxId($sandboxId, $inboxId);
     }
 
     /**
-     * Get message attachments by inboxId and messageId.
+     * Get message attachments by sandboxId and messageId.
      *
      * @param int         $messageId
      * @param string|null $attachmentType
@@ -45,7 +52,7 @@ public function getMessageAttachments(
                 '%s/api/accounts/%s/inboxes/%s/messages/%s/attachments',
                 $this->getHost(),
                 $this->getAccountId(),
-                $this->getInboxId(),
+                $this->getSandboxId(),
                 $messageId
             ),
             $parameters
@@ -66,7 +73,7 @@ public function getMessageAttachment(int $messageId, int $attachmentId): Respons
             '%s/api/accounts/%s/inboxes/%s/messages/%s/attachments/%s',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId,
             $attachmentId
         )));
@@ -76,9 +83,4 @@ public function getAccountId(): int
     {
         return $this->accountId;
     }
-
-    public function getInboxId(): int
-    {
-        return $this->inboxId;
-    }
 }
diff --git a/src/Api/Sandbox/Emails.php b/src/Api/Sandbox/Emails.php
index d0dc42c..1e48731 100644
--- a/src/Api/Sandbox/Emails.php
+++ b/src/Api/Sandbox/Emails.php
@@ -14,15 +14,21 @@
  */
 class Emails extends AbstractEmails implements SandboxInterface
 {
-    public function __construct(ConfigInterface $config, private int $inboxId)
+    use SandboxIdTrait;
+
+    /**
+     * @param int|null $inboxId deprecated, use $sandboxId instead
+     */
+    public function __construct(ConfigInterface $config, ?int $sandboxId = null, ?int $inboxId = null)
     {
         parent::__construct($config);
+        $this->setSandboxId($sandboxId, $inboxId);
     }
 
     public function send(Email $email): ResponseInterface
     {
         return $this->handleResponse(
-            $this->httpPost(sprintf('%s/api/send/%s', $this->getHost(), $this->getInboxId()), [], $this->getPayload($email))
+            $this->httpPost(sprintf('%s/api/send/%s', $this->getHost(), $this->getSandboxId()), [], $this->getPayload($email))
         );
     }
 
@@ -30,7 +36,7 @@ public function batchSend(array $recipientEmails, ?Email $baseEmail = null): Res
     {
         return $this->handleResponse(
             $this->httpPost(
-                sprintf('%s/api/batch/%s', $this->getHost(), $this->getInboxId()),
+                sprintf('%s/api/batch/%s', $this->getHost(), $this->getSandboxId()),
                 [],
                 $this->getBatchBody($recipientEmails, $baseEmail),
             )
@@ -41,9 +47,4 @@ protected function getHost(): string
     {
         return $this->config->getHost() ?: self::SENDMAIL_SANDBOX_HOST;
     }
-
-    public function getInboxId(): int
-    {
-        return $this->inboxId;
-    }
 }
diff --git a/src/Api/Sandbox/Inbox.php b/src/Api/Sandbox/Inbox.php
index d649bd8..271776a 100644
--- a/src/Api/Sandbox/Inbox.php
+++ b/src/Api/Sandbox/Inbox.php
@@ -4,180 +4,78 @@
 
 namespace Mailtrap\Api\Sandbox;
 
-use Mailtrap\Api\AbstractApi;
 use Mailtrap\ConfigInterface;
-use Mailtrap\DTO\Request\Inbox as InboxRequest;
-use Mailtrap\Exception\RuntimeException;
+use Mailtrap\DTO\Request\Sandbox as SandboxRequest;
+use Mailtrap\Helper\Deprecation;
 use Psr\Http\Message\ResponseInterface;
 
 /**
+ * The overrides below only keep the old parameter names, so calls with named arguments keep working.
+ *
+ * @deprecated Use {@see Sandbox} (MailtrapSandboxClient::sandboxes()) instead.
+ * @psalm-suppress ParamNameMismatch
+ *
  * Class Inbox
  */
-class Inbox extends AbstractApi implements SandboxInterface
+class Inbox extends Sandbox
 {
-    public function __construct(ConfigInterface $config, private int $accountId)
+    public function __construct(ConfigInterface $config, int $accountId)
     {
-        parent::__construct($config);
-    }
+        Deprecation::trigger(
+            self::class . ' (MailtrapSandboxClient::inboxes())',
+            Sandbox::class . ' (MailtrapSandboxClient::sandboxes())'
+        );
 
-    /**
-     * Get a list of inboxes.
-     *
-     * @return ResponseInterface
-     */
-    public function getList(): ResponseInterface
-    {
-        return $this->handleResponse($this->httpGet(
-            sprintf('%s/api/accounts/%s/inboxes', $this->getHost(), $this->getAccountId())
-        ));
+        parent::__construct($config, $accountId);
     }
 
     /**
-     * Get inbox attributes by inbox id. See the list of attributes in the example
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
+     * @deprecated Use {@see Sandbox::getSandboxAttributes()} instead.
      */
     public function getInboxAttributes(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpGet(
-            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        Deprecation::trigger(__METHOD__ . '()', Sandbox::class . '::getSandboxAttributes()');
+
+        return $this->getSandboxAttributes($inboxId);
     }
 
-    /**
-     * Create an inbox in a project.
-     *
-     * @param int    $projectId
-     * @param string $inboxName
-     *
-     * @return ResponseInterface
-     */
     public function create(int $projectId, string $inboxName): ResponseInterface
     {
-        return $this->handleResponse(
-            $this->httpPost(
-                sprintf('%s/api/accounts/%s/projects/%s/inboxes', $this->getHost(), $this->getAccountId(), $projectId),
-                [],
-                ['inbox' => ['name' => $inboxName]]
-            )
-        );
+        return parent::create($projectId, $inboxName);
     }
 
-    /**
-     * Delete an inbox with all its emails.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function delete(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpDelete(
-            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        return parent::delete($inboxId);
     }
 
-    /**
-     * Update inbox name and/or inbox email username.
-     *
-     * @param int          $inboxId
-     * @param InboxRequest $updateInbox
-     *
-     * @return ResponseInterface
-     */
-    public function update(int $inboxId, InboxRequest $updateInbox): ResponseInterface
+    public function update(int $inboxId, SandboxRequest $updateInbox): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $inboxId),
-            [],
-            ['inbox' => $this->getUpdatePayload($updateInbox)]
-        ));
+        return parent::update($inboxId, $updateInbox);
     }
 
-    /**
-     * Delete all messages (emails) from inbox.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function clean(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/clean', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        return parent::clean($inboxId);
     }
 
-    /**
-     * Mark all messages in the inbox as read.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function markAsRead(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/all_read', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        return parent::markAsRead($inboxId);
     }
 
-    /**
-     * Reset SMTP credentials of the inbox.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function resetSmtpCredentials(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/reset_credentials', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        return parent::resetSmtpCredentials($inboxId);
     }
 
-    /**
-     * Turn the email address of the inbox on/off.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function toggleEmailAddress(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/toggle_email_username', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
+        return parent::toggleEmailAddress($inboxId);
     }
 
-    /**
-     * Reset username of email address per inbox.
-     *
-     * @param int $inboxId
-     *
-     * @return ResponseInterface
-     */
     public function resetEmailAddress(int $inboxId): ResponseInterface
     {
-        return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/reset_email_username', $this->getHost(), $this->getAccountId(), $inboxId)
-        ));
-    }
-
-    private function getUpdatePayload(InboxRequest $updateInbox): array
-    {
-        $result = $updateInbox->toArray();
-        if (empty($result)) {
-            throw new RuntimeException('At least one inbox parameter should be populated ("name" or "email_username")');
-        }
-
-        return $result;
-    }
-
-    public function getAccountId(): int
-    {
-        return $this->accountId;
+        return parent::resetEmailAddress($inboxId);
     }
 }
diff --git a/src/Api/Sandbox/Message.php b/src/Api/Sandbox/Message.php
index 85d3e56..47c5c75 100644
--- a/src/Api/Sandbox/Message.php
+++ b/src/Api/Sandbox/Message.php
@@ -14,16 +14,23 @@
  */
 class Message extends AbstractApi implements SandboxInterface
 {
+    use SandboxIdTrait;
+
+    /**
+     * @param int|null $inboxId deprecated, use $sandboxId instead
+     */
     public function __construct(
         ConfigInterface $config,
         private int $accountId,
-        private int $inboxId,
+        ?int $sandboxId = null,
+        ?int $inboxId = null,
     ) {
         parent::__construct($config);
+        $this->setSandboxId($sandboxId, $inboxId);
     }
 
     /**
-     * Get all messages in the inbox
+     * Get all messages in the sandbox
      * Note: if you want to get all messages you need to use "page" param (by default will return only 30 messages per
      * page)
      *
@@ -56,7 +63,7 @@ public function getList(
         }
 
         return $this->handleResponse($this->httpGet(
-            sprintf('%s/api/accounts/%s/inboxes/%s/messages', $this->getHost(), $this->getAccountId(), $this->getInboxId()),
+            sprintf('%s/api/accounts/%s/inboxes/%s/messages', $this->getHost(), $this->getAccountId(), $this->getSandboxId()),
             $parameters
         ));
     }
@@ -71,7 +78,7 @@ public function getList(
     public function getById(int $messageId): ResponseInterface
     {
         return $this->handleResponse($this->httpGet(
-            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getInboxId(), $messageId)
+            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getSandboxId(), $messageId)
         ));
     }
 
@@ -88,7 +95,7 @@ public function getSpamScore(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/spam_report',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -106,7 +113,7 @@ public function getHtmlAnalysis(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/analyze',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -124,7 +131,7 @@ public function getMailHeaders(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/mail_headers',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -142,7 +149,7 @@ public function getText(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/body.txt',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -160,7 +167,7 @@ public function getRaw(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/body.raw',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -178,7 +185,7 @@ public function getHtml(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/body.html',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -196,7 +203,7 @@ public function getEml( int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/body.eml',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -214,7 +221,7 @@ public function getSource(int $messageId): ResponseInterface
             '%s/api/accounts/%s/inboxes/%s/messages/%s/body.htmlsource',
             $this->getHost(),
             $this->getAccountId(),
-            $this->getInboxId(),
+            $this->getSandboxId(),
             $messageId
         )));
     }
@@ -230,7 +237,7 @@ public function getSource(int $messageId): ResponseInterface
     public function markAsRead(int $messageId, bool $isRead = true): ResponseInterface
     {
         return $this->handleResponse($this->httpPatch(
-            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getInboxId(), $messageId),
+            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getSandboxId(), $messageId),
             [],
             [
                 'message' => [
@@ -241,7 +248,7 @@ public function markAsRead(int $messageId, bool $isRead = true): ResponseInterfa
     }
 
     /**
-     * Delete message from inbox.
+     * Delete message from sandbox.
      *
      * @param int $messageId
      *
@@ -250,7 +257,7 @@ public function markAsRead(int $messageId, bool $isRead = true): ResponseInterfa
     public function delete(int $messageId): ResponseInterface
     {
         return $this->handleResponse($this->httpDelete(
-            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getInboxId(), $messageId)
+            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s', $this->getHost(), $this->getAccountId(), $this->getSandboxId(), $messageId)
         ));
     }
 
@@ -269,7 +276,7 @@ public function forward(int $messageId, string $email): ResponseInterface
         }
 
         return $this->handleResponse($this->httpPost(
-            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s/forward', $this->getHost(), $this->getAccountId(), $this->getInboxId(), $messageId),
+            sprintf('%s/api/accounts/%s/inboxes/%s/messages/%s/forward', $this->getHost(), $this->getAccountId(), $this->getSandboxId(), $messageId),
             [],
             ['email' => $email]
         ));
@@ -279,9 +286,4 @@ public function getAccountId(): int
     {
         return $this->accountId;
     }
-
-    public function getInboxId(): int
-    {
-        return $this->inboxId;
-    }
 }
diff --git a/src/Api/Sandbox/Project.php b/src/Api/Sandbox/Project.php
index e4dced0..90fa340 100644
--- a/src/Api/Sandbox/Project.php
+++ b/src/Api/Sandbox/Project.php
@@ -19,7 +19,7 @@ public function __construct(ConfigInterface $config, private int $accountId)
     }
 
     /**
-     * List projects and their inboxes to which the API token has access.
+     * List projects and their sandboxes to which the API token has access.
      *
      * @return ResponseInterface
      */
@@ -31,7 +31,7 @@ public function getList(): ResponseInterface
     }
 
     /**
-     * Get the project and its inboxes.
+     * Get the project and its sandboxes.
      *
      * @param int $projectId
      *
@@ -61,7 +61,7 @@ public function create(string $projectName): ResponseInterface
     }
 
     /**
-     * Delete project and its inboxes.
+     * Delete project and its sandboxes.
      *
      * @param int $projectId
      *
diff --git a/src/Api/Sandbox/Sandbox.php b/src/Api/Sandbox/Sandbox.php
new file mode 100644
index 0000000..3e6b951
--- /dev/null
+++ b/src/Api/Sandbox/Sandbox.php
@@ -0,0 +1,183 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\Api\Sandbox;
+
+use Mailtrap\Api\AbstractApi;
+use Mailtrap\ConfigInterface;
+use Mailtrap\DTO\Request\Sandbox as SandboxRequest;
+use Mailtrap\Exception\RuntimeException;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * Class Sandbox
+ */
+class Sandbox extends AbstractApi implements SandboxInterface
+{
+    public function __construct(ConfigInterface $config, private int $accountId)
+    {
+        parent::__construct($config);
+    }
+
+    /**
+     * Get a list of sandboxes.
+     *
+     * @return ResponseInterface
+     */
+    public function getList(): ResponseInterface
+    {
+        return $this->handleResponse($this->httpGet(
+            sprintf('%s/api/accounts/%s/inboxes', $this->getHost(), $this->getAccountId())
+        ));
+    }
+
+    /**
+     * Get sandbox attributes by sandbox id. See the list of attributes in the example
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function getSandboxAttributes(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpGet(
+            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Create a sandbox in a project.
+     *
+     * @param int    $projectId
+     * @param string $sandboxName
+     *
+     * @return ResponseInterface
+     */
+    public function create(int $projectId, string $sandboxName): ResponseInterface
+    {
+        return $this->handleResponse(
+            $this->httpPost(
+                sprintf('%s/api/accounts/%s/projects/%s/inboxes', $this->getHost(), $this->getAccountId(), $projectId),
+                [],
+                ['inbox' => ['name' => $sandboxName]]
+            )
+        );
+    }
+
+    /**
+     * Delete a sandbox with all its emails.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function delete(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpDelete(
+            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Update sandbox name and/or sandbox email username.
+     *
+     * @param int            $sandboxId
+     * @param SandboxRequest $sandbox
+     *
+     * @return ResponseInterface
+     */
+    public function update(int $sandboxId, SandboxRequest $sandbox): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s', $this->getHost(), $this->getAccountId(), $sandboxId),
+            [],
+            ['inbox' => $this->getUpdatePayload($sandbox)]
+        ));
+    }
+
+    /**
+     * Delete all messages (emails) from sandbox.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function clean(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s/clean', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Mark all messages in the sandbox as read.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function markAsRead(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s/all_read', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Reset SMTP credentials of the sandbox.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function resetSmtpCredentials(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s/reset_credentials', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Turn the email address of the sandbox on/off.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function toggleEmailAddress(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s/toggle_email_username', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    /**
+     * Reset username of email address per sandbox.
+     *
+     * @param int $sandboxId
+     *
+     * @return ResponseInterface
+     */
+    public function resetEmailAddress(int $sandboxId): ResponseInterface
+    {
+        return $this->handleResponse($this->httpPatch(
+            sprintf('%s/api/accounts/%s/inboxes/%s/reset_email_username', $this->getHost(), $this->getAccountId(), $sandboxId)
+        ));
+    }
+
+    private function getUpdatePayload(SandboxRequest $sandbox): array
+    {
+        $result = $sandbox->toArray();
+        if (empty($result)) {
+            throw new RuntimeException('At least one sandbox parameter should be populated ("name" or "email_username")');
+        }
+
+        return $result;
+    }
+
+    public function getAccountId(): int
+    {
+        return $this->accountId;
+    }
+}
diff --git a/src/Api/Sandbox/SandboxIdTrait.php b/src/Api/Sandbox/SandboxIdTrait.php
new file mode 100644
index 0000000..7300021
--- /dev/null
+++ b/src/Api/Sandbox/SandboxIdTrait.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\Api\Sandbox;
+
+use Mailtrap\Exception\InvalidArgumentException;
+use Mailtrap\Helper\Deprecation;
+
+/**
+ * The sandbox id of a sandbox-scoped API. Constructors still accept it under its deprecated name, $inboxId.
+ *
+ * @internal
+ */
+trait SandboxIdTrait
+{
+    private int $sandboxId;
+
+    public function getSandboxId(): int
+    {
+        return $this->sandboxId;
+    }
+
+    /**
+     * @deprecated Use getSandboxId() instead.
+     */
+    public function getInboxId(): int
+    {
+        Deprecation::trigger(self::class . '::getInboxId()', self::class . '::getSandboxId()');
+
+        return $this->sandboxId;
+    }
+
+    private function setSandboxId(?int $sandboxId, ?int $inboxId): void
+    {
+        $sandboxId = Deprecation::renamedArgument(
+            self::class . '::__construct()',
+            'inboxId',
+            'sandboxId',
+            $inboxId,
+            $sandboxId
+        );
+
+        if (null === $sandboxId) {
+            throw new InvalidArgumentException(sprintf('%s::__construct() requires the $sandboxId argument.', self::class));
+        }
+
+        $this->sandboxId = $sandboxId;
+    }
+}
diff --git a/src/Api/Sending/CompanyInfo.php b/src/Api/Sending/CompanyInfo.php
index 2160fae..2da416f 100644
--- a/src/Api/Sending/CompanyInfo.php
+++ b/src/Api/Sending/CompanyInfo.php
@@ -21,7 +21,7 @@ public function __construct(ConfigInterface $config, private int $domainId)
     }
 
     /**
-     * Get the company info associated with the sending domain.
+     * Get the company info associated with the domain.
      *
      * @return ResponseInterface
      */
@@ -33,7 +33,7 @@ public function getCompanyInfo(): ResponseInterface
     }
 
     /**
-     * Create the company info for the sending domain. Company info is required
+     * Create the company info for the domain. Company info is required
      * for domain compliance verification.
      *
      * @param CreateCompanyInfo $companyInfo
@@ -52,7 +52,7 @@ public function createCompanyInfo(CreateCompanyInfo $companyInfo): ResponseInter
     }
 
     /**
-     * Update the company info for the sending domain.
+     * Update the company info for the domain.
      *
      * @param UpdateCompanyInfo $companyInfo
      * @return ResponseInterface
diff --git a/src/Api/Sending/Domain.php b/src/Api/Sending/Domain.php
index 5496749..70fad4a 100644
--- a/src/Api/Sending/Domain.php
+++ b/src/Api/Sending/Domain.php
@@ -7,6 +7,7 @@
 use Mailtrap\Api\AbstractApi;
 use Mailtrap\ConfigInterface;
 use Mailtrap\DTO\Request\Domain\UpdateDomain;
+use Mailtrap\Helper\Deprecation;
 use Psr\Http\Message\ResponseInterface;
 
 /**
@@ -20,11 +21,11 @@ public function __construct(ConfigInterface $config, private int $accountId)
     }
 
     /**
-     * Get a list of sending domains.
+     * Get a list of domains.
      *
      * @return ResponseInterface
      */
-    public function getSendingDomains(): ResponseInterface
+    public function getDomains(): ResponseInterface
     {
         return $this->handleResponse(
             $this->httpGet($this->getBasePath())
@@ -32,12 +33,12 @@ public function getSendingDomains(): ResponseInterface
     }
 
     /**
-     * Create a new sending domain.
+     * Create a new domain.
      *
      * @param string $domainName
      * @return ResponseInterface
      */
-    public function createSendingDomain(string $domainName): ResponseInterface
+    public function createDomain(string $domainName): ResponseInterface
     {
         return $this->handleResponse(
             $this->httpPost(
@@ -52,7 +53,7 @@ public function createSendingDomain(string $domainName): ResponseInterface
     }
 
     /**
-     * Get a sending domain by ID.
+     * Get a domain by ID.
      *
      * @param int $domainId
      * @return ResponseInterface
@@ -67,13 +68,13 @@ public function getDomainById(int $domainId): ResponseInterface
     }
 
     /**
-     * Update configuration settings for a sending domain.
+     * Update configuration settings for a domain.
      *
      * @param int          $domainId
      * @param UpdateDomain $domain
      * @return ResponseInterface
      */
-    public function updateSendingDomain(int $domainId, UpdateDomain $domain): ResponseInterface
+    public function updateDomain(int $domainId, UpdateDomain $domain): ResponseInterface
     {
         return $this->handleResponse(
             $this->httpPatch(
@@ -86,12 +87,12 @@ public function updateSendingDomain(int $domainId, UpdateDomain $domain): Respon
     }
 
     /**
-     * Delete a sending domain by ID.
+     * Delete a domain by ID.
      *
      * @param int $domainId
      * @return ResponseInterface
      */
-    public function deleteSendingDomain(int $domainId): ResponseInterface
+    public function deleteDomain(int $domainId): ResponseInterface
     {
         return $this->handleResponse(
             $this->httpDelete(
@@ -101,7 +102,7 @@ public function deleteSendingDomain(int $domainId): ResponseInterface
     }
 
     /**
-     * Send sending domain setup instructions.
+     * Send domain setup instructions.
      *
      * @param int $domainId
      * @param string $email
@@ -119,6 +120,46 @@ public function sendDomainSetupInstructions(int $domainId, string $email): Respo
         );
     }
 
+    /**
+     * @deprecated Use getDomains() instead.
+     */
+    public function getSendingDomains(): ResponseInterface
+    {
+        Deprecation::trigger(__METHOD__ . '()', self::class . '::getDomains()');
+
+        return $this->getDomains();
+    }
+
+    /**
+     * @deprecated Use createDomain() instead.
+     */
+    public function createSendingDomain(string $domainName): ResponseInterface
+    {
+        Deprecation::trigger(__METHOD__ . '()', self::class . '::createDomain()');
+
+        return $this->createDomain($domainName);
+    }
+
+    /**
+     * @deprecated Use updateDomain() instead.
+     */
+    public function updateSendingDomain(int $domainId, UpdateDomain $domain): ResponseInterface
+    {
+        Deprecation::trigger(__METHOD__ . '()', self::class . '::updateDomain()');
+
+        return $this->updateDomain($domainId, $domain);
+    }
+
+    /**
+     * @deprecated Use deleteDomain() instead.
+     */
+    public function deleteSendingDomain(int $domainId): ResponseInterface
+    {
+        Deprecation::trigger(__METHOD__ . '()', self::class . '::deleteDomain()');
+
+        return $this->deleteDomain($domainId);
+    }
+
     private function getBasePath(): string
     {
         return sprintf('%s/api/accounts/%s/sending_domains', $this->getHost(), $this->accountId);
diff --git a/src/Api/Sending/EmailLogs.php b/src/Api/Sending/EmailLogs.php
index 5a6da29..b323e36 100644
--- a/src/Api/Sending/EmailLogs.php
+++ b/src/Api/Sending/EmailLogs.php
@@ -26,7 +26,7 @@ public function __construct(ConfigInterface $config, private int $accountId)
     /**
      * List email logs (paginated).
      *
-     * Returns a paginated list of email logs for the account. Results are restricted to sending domains
+     * Returns a paginated list of email logs for the account. Results are restricted to domains
      * the authenticated token has access to. Invalid or unknown filters are ignored.
      * Results are ordered by sent_at descending.
      *
@@ -58,7 +58,7 @@ public function getList(array|EmailLogsListFilters $filters = [], ?string $searc
     /**
      * Get a single email log message by ID.
      *
-     * Returns message details including events. Message must belong to the account and a sending domain
+     * Returns message details including events. Message must belong to the account and a domain
      * the token can access.
      *
      * @param string $sendingMessageId Message UUID (sending_message_id).
diff --git a/src/Api/Sending/TrackingOptOut.php b/src/Api/Sending/TrackingOptOut.php
index ab6b839..bd0debb 100644
--- a/src/Api/Sending/TrackingOptOut.php
+++ b/src/Api/Sending/TrackingOptOut.php
@@ -33,7 +33,7 @@ public function getTrackingOptOuts(?TrackingOptOutsFilter $filter = null): Respo
     }
 
     /**
-     * Add an email address to the tracking opt-out list for a sending domain.
+     * Add an email address to the tracking opt-out list for a domain.
      *
      * @param CreateTrackingOptOut $trackingOptOut
      * @return ResponseInterface
diff --git a/src/Bridge/Laravel/README.md b/src/Bridge/Laravel/README.md
index 41315c6..e8566dc 100644
--- a/src/Bridge/Laravel/README.md
+++ b/src/Bridge/Laravel/README.md
@@ -59,7 +59,7 @@ MAILTRAP_HOST="bulk.api.mailtrap.io"
 MAILTRAP_API_KEY="YOUR_API_KEY_HERE"
 ```
 ### Sandbox
-You need to set the API key to the `MAILTRAP_API_KEY` variable and set your inboxId to the `MAILTRAP_INBOX_ID`.
+You need to set the API key to the `MAILTRAP_API_KEY` variable and set your sandbox ID to the `MAILTRAP_SANDBOX_ID`.
 
 More info sandbox -> https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing
 ```bash
@@ -67,8 +67,9 @@ MAIL_MAILER="mailtrap-sdk"
 
 MAILTRAP_HOST="sandbox.api.mailtrap.io"
 MAILTRAP_API_KEY="YOUR_API_KEY_HERE"
-MAILTRAP_INBOX_ID=1000001
+MAILTRAP_SANDBOX_ID=1000001
 ```
+The deprecated `MAILTRAP_INBOX_ID` variable and `inboxId` key still work. If your `config/services.php` defines its own `mailtrap-sdk` entry, it replaces the package's default one as a whole, so change its `inboxId` key to `'sandboxId' => env('MAILTRAP_SANDBOX_ID')` when you rename the variable.
 
 Before starting, run the clear configuration cache command to set up new variables.
 ```bash
@@ -358,7 +359,7 @@ Please add them manually to the `config/services.php` file and after that run th
 'mailtrap-sdk' => [
     'host' => env('MAILTRAP_HOST', 'send.api.mailtrap.io'),
     'apiKey' => env('MAILTRAP_API_KEY'),
-    'inboxId' => env('MAILTRAP_INBOX_ID'),
+    'sandboxId' => env('MAILTRAP_SANDBOX_ID'),
 ],
 ```
 
diff --git a/src/Bridge/Laravel/config/mailtrap-sdk.php b/src/Bridge/Laravel/config/mailtrap-sdk.php
index ca3e5e4..3ae4b02 100644
--- a/src/Bridge/Laravel/config/mailtrap-sdk.php
+++ b/src/Bridge/Laravel/config/mailtrap-sdk.php
@@ -4,6 +4,7 @@
     'mailtrap-sdk' => [
         'host' => env('MAILTRAP_HOST', 'send.api.mailtrap.io'),
         'apiKey' => env('MAILTRAP_API_KEY'),
-        'inboxId' => env('MAILTRAP_INBOX_ID'),
+        'sandboxId' => env('MAILTRAP_SANDBOX_ID'),
+        'inboxId' => env('MAILTRAP_INBOX_ID'), // deprecated, use MAILTRAP_SANDBOX_ID
     ],
 ];
diff --git a/src/Bridge/Symfony/README.md b/src/Bridge/Symfony/README.md
index 94293b5..6322568 100644
--- a/src/Bridge/Symfony/README.md
+++ b/src/Bridge/Symfony/README.md
@@ -39,12 +39,13 @@ MAILER_DSN=mailtrap+sdk://YOUR_API_KEY_HERE@bulk.api.mailtrap.io
 ```
 
 ### Sandbox
-Add or change MAILER_DSN variable inside your `.env` file. Also, you need to change the `YOUR_API_KEY_HERE` placeholder and put correct `inboxId`.
+Add or change MAILER_DSN variable inside your `.env` file. Also, you need to change the `YOUR_API_KEY_HERE` placeholder and put correct `sandboxId`.
 
 More info sandbox -> https://help.mailtrap.io/article/109-getting-started-with-mailtrap-email-testing
 ```bash
-MAILER_DSN=mailtrap+sdk://YOUR_API_KEY_HERE@sandbox.api.mailtrap.io?inboxId=1000001
+MAILER_DSN=mailtrap+sdk://YOUR_API_KEY_HERE@sandbox.api.mailtrap.io?sandboxId=1000001
 ```
+The deprecated `inboxId` option still works.
 
 ### Send you first email
 
diff --git a/src/Bridge/Transport/MailtrapSdkTransport.php b/src/Bridge/Transport/MailtrapSdkTransport.php
index 9174811..31ac366 100644
--- a/src/Bridge/Transport/MailtrapSdkTransport.php
+++ b/src/Bridge/Transport/MailtrapSdkTransport.php
@@ -65,12 +65,12 @@ protected function doSend(SentMessage $message): void
 
     private function getEndpoint(): string
     {
-        $inboxId = null;
+        $sandboxId = null;
         if ($this->emailsSendApiLayer instanceof SandboxEmails) {
-            $inboxId = $this->emailsSendApiLayer->getInboxId();
+            $sandboxId = $this->emailsSendApiLayer->getSandboxId();
         }
 
-        return $this->config->getHost() . (null === $inboxId ? '' : '?inboxId=' . $inboxId);
+        return $this->config->getHost() . (null === $sandboxId ? '' : '?sandboxId=' . $sandboxId);
     }
 
     private function getEnvelopeRecipients(Email $email, Envelope $envelope): array
diff --git a/src/Bridge/Transport/MailtrapSdkTransportFactory.php b/src/Bridge/Transport/MailtrapSdkTransportFactory.php
index b6d08f1..d5d5b65 100644
--- a/src/Bridge/Transport/MailtrapSdkTransportFactory.php
+++ b/src/Bridge/Transport/MailtrapSdkTransportFactory.php
@@ -7,8 +7,10 @@
 use Mailtrap\Api\AbstractApi;
 use Mailtrap\Config;
 use Mailtrap\EmailsSendMailtrapClientInterface;
+use Mailtrap\Exception\InvalidArgumentException;
 use Mailtrap\Exception\RuntimeException;
 use Mailtrap\Exception\Transport\UnsupportedHostException;
+use Mailtrap\Helper\Deprecation;
 use Mailtrap\MailtrapClient;
 use Mailtrap\MailtrapSandboxClient;
 use Symfony\Component\HttpClient\Psr18Client;
@@ -28,7 +30,7 @@ public function create(Dsn $dsn): TransportInterface
             throw new UnsupportedSchemeException($dsn, 'mailtrap+sdk', $this->getSupportedSchemes());
         }
 
-        $inboxId = !empty($dsn->getOption('inboxId')) ? (int) $dsn->getOption('inboxId') : null;
+        $sandboxId = $this->getSandboxId($dsn);
         $config = (new Config($this->getUser($dsn)))
             ->setHost('default' === $dsn->getHost() ? AbstractApi::SENDMAIL_TRANSACTIONAL_HOST : $dsn->getHost())
             ->setHttpClient(null === $this->client ? null : new Psr18Client($this->client))
@@ -36,13 +38,13 @@ public function create(Dsn $dsn): TransportInterface
 
         $emailsSendMailtrapClient = $this->getEmailsSendMailTrapClient($config);
         if ($emailsSendMailtrapClient instanceof MailtrapSandboxClient) {
-            if (null === $inboxId) {
+            if (!$sandboxId) {
                 throw new RuntimeException(
-                    'You cannot send an email to a sandbox with an empty "inboxId" parameter. Example -> "MAILER_DSN=mailtrap+sdk://APIKEY@sandbox.api.mailtrap.io?inboxId=1234"'
+                    'You cannot send an email to a sandbox with an empty "sandboxId" parameter. Example -> "MAILER_DSN=mailtrap+sdk://APIKEY@sandbox.api.mailtrap.io?sandboxId=1234"'
                 );
             }
 
-            $emailsSendApiLayer = $emailsSendMailtrapClient->emails($inboxId);
+            $emailsSendApiLayer = $emailsSendMailtrapClient->emails($sandboxId);
         } else {
             $emailsSendApiLayer = $emailsSendMailtrapClient->emails();
         }
@@ -55,6 +57,44 @@ protected function getSupportedSchemes(): array
         return ['mailtrap+sdk'];
     }
 
+    /**
+     * Reads the "sandboxId" option, falling back to the deprecated "inboxId" one. In Laravel these are the
+     * services.mailtrap-sdk config keys, set from MAILTRAP_SANDBOX_ID and MAILTRAP_INBOX_ID. Setting both to
+     * different values, a zero included, is an error, as passing both arguments to
+     * MailtrapClient::initSendingEmails() is.
+     */
+    private function getSandboxId(Dsn $dsn): ?int
+    {
+        $sandboxId = $this->getIdOption($dsn, 'sandboxId');
+        $inboxId = $this->getIdOption($dsn, 'inboxId');
+        if (null === $inboxId) {
+            return $sandboxId;
+        }
+
+        Deprecation::trigger(
+            'The "inboxId" option of the mailtrap+sdk transport (MAILTRAP_INBOX_ID in Laravel)',
+            'the "sandboxId" option (MAILTRAP_SANDBOX_ID)'
+        );
+
+        if (null !== $sandboxId && $sandboxId !== $inboxId) {
+            throw new InvalidArgumentException(
+                'The mailtrap+sdk transport received different values for the "sandboxId" and "inboxId" options (MAILTRAP_SANDBOX_ID and MAILTRAP_INBOX_ID in Laravel); set only "sandboxId".'
+            );
+        }
+
+        return $inboxId;
+    }
+
+    /**
+     * An option left empty, such as an empty MAILTRAP_SANDBOX_ID in Laravel, is unset.
+     */
+    private function getIdOption(Dsn $dsn, string $option): ?int
+    {
+        $value = $dsn->getOption($option);
+
+        return null === $value || '' === $value ? null : (int) $value;
+    }
+
     private function getEmailsSendMailTrapClient(Config $config): EmailsSendMailtrapClientInterface
     {
         $layer = $this->determineLayerNameByHost($config->getHost());
diff --git a/src/DTO/Request/Domain/CreateCompanyInfo.php b/src/DTO/Request/Domain/CreateCompanyInfo.php
index d3b91a4..53ed5cd 100644
--- a/src/DTO/Request/Domain/CreateCompanyInfo.php
+++ b/src/DTO/Request/Domain/CreateCompanyInfo.php
@@ -7,7 +7,7 @@
 /**
  * Class CreateCompanyInfo
  *
- * Company information for a sending domain. Required for domain compliance
+ * Company information for a domain. Required for domain compliance
  * verification.
  */
 final class CreateCompanyInfo implements DomainInterface
diff --git a/src/DTO/Request/Domain/UpdateDomain.php b/src/DTO/Request/Domain/UpdateDomain.php
index f6c8c2b..3d17c53 100644
--- a/src/DTO/Request/Domain/UpdateDomain.php
+++ b/src/DTO/Request/Domain/UpdateDomain.php
@@ -9,7 +9,7 @@
 /**
  * Class UpdateDomain
  *
- * Configuration settings for a sending domain. Only the fields provided are
+ * Configuration settings for a domain. Only the fields provided are
  * updated.
  */
 final class UpdateDomain implements DomainInterface
@@ -58,7 +58,7 @@ public function toArray(): array
 
         if ($payload === []) {
             throw new InvalidArgumentException(
-                'At least one updatable field must be provided to update a sending domain'
+                'At least one updatable field must be provided to update a domain'
             );
         }
 
diff --git a/src/DTO/Request/EmailCampaign/CreateEmailCampaign.php b/src/DTO/Request/EmailCampaign/CreateEmailCampaign.php
index 98723bd..fabe192 100644
--- a/src/DTO/Request/EmailCampaign/CreateEmailCampaign.php
+++ b/src/DTO/Request/EmailCampaign/CreateEmailCampaign.php
@@ -15,7 +15,7 @@ final class CreateEmailCampaign implements EmailCampaignInterface
 {
     /**
      * @param string             $name               Campaign name (required)
-     * @param int                $domainId           ID of the verified sending domain, as returned by the Sending Domains endpoints (required)
+     * @param int                $domainId           ID of the verified domain, as returned by the Domains endpoints (required)
      * @param string             $fromLocalPart      Local part (before the @) of the From address (required)
      * @param TemplateAttributes $templateAttributes Template attributes; `subject` is required on create
      * @param string|null        $fromDisplayName    Display name shown in the From header
diff --git a/src/DTO/Request/EmailCampaign/UpdateEmailCampaign.php b/src/DTO/Request/EmailCampaign/UpdateEmailCampaign.php
index 13f8b75..5d42f3c 100644
--- a/src/DTO/Request/EmailCampaign/UpdateEmailCampaign.php
+++ b/src/DTO/Request/EmailCampaign/UpdateEmailCampaign.php
@@ -16,7 +16,7 @@ final class UpdateEmailCampaign implements EmailCampaignInterface
 {
     /**
      * @param string|null             $name               Campaign name
-     * @param int|null                $domainId           ID of the verified sending domain, as returned by the Sending Domains endpoints
+     * @param int|null                $domainId           ID of the verified domain, as returned by the Domains endpoints
      * @param string|null             $fromDisplayName    Display name shown in the From header
      * @param string|null             $fromLocalPart      Local part (before the @) of the From address
      * @param string|null             $deliveryMode       One of EmailCampaignInterface::DELIVERY_MODE_*
diff --git a/src/DTO/Request/Inbox.php b/src/DTO/Request/Inbox.php
index 8f487e3..15b6546 100644
--- a/src/DTO/Request/Inbox.php
+++ b/src/DTO/Request/Inbox.php
@@ -4,43 +4,19 @@
 
 namespace Mailtrap\DTO\Request;
 
+use Mailtrap\Helper\Deprecation;
+
 /**
- * Class UpdateInbox
+ * @deprecated Use {@see Sandbox} instead.
+ *
+ * Class Inbox
  */
-class Inbox implements RequestInterface
+class Inbox extends Sandbox
 {
-    public function __construct(private ?string $name = null, private ?string $emailUsername = null)
-    {
-    }
-
-    /**
-     * @return string|null
-     */
-    public function getName(): ?string
-    {
-        return $this->name;
-    }
-
-    /**
-     * @return string|null
-     */
-    public function getEmailUsername(): ?string
-    {
-        return $this->emailUsername;
-    }
-
-    public function toArray(): array
+    public function __construct(?string $name = null, ?string $emailUsername = null)
     {
-        $array = [];
-
-        if (!empty($this->getName())) {
-            $array['name'] = $this->getName();
-        }
-
-        if (!empty($this->getEmailUsername())) {
-            $array['email_username'] = $this->getEmailUsername();
-        }
+        Deprecation::trigger(self::class, Sandbox::class);
 
-        return $array;
+        parent::__construct($name, $emailUsername);
     }
 }
diff --git a/src/DTO/Request/MarketingStats/MarketingStatsFilter.php b/src/DTO/Request/MarketingStats/MarketingStatsFilter.php
index 8ec2823..3f08cba 100644
--- a/src/DTO/Request/MarketingStats/MarketingStatsFilter.php
+++ b/src/DTO/Request/MarketingStats/MarketingStatsFilter.php
@@ -17,7 +17,7 @@ final class MarketingStatsFilter implements MarketingStatsInterface
     /**
      * @param string   $startDate             Start of the date range (inclusive), `YYYY-MM-DD`
      * @param string   $endDate               End of the date range (inclusive), `YYYY-MM-DD`
-     * @param int[]    $sendingDomainIds      Only traffic sent from these sending domains
+     * @param int[]    $sendingDomainIds      Only traffic sent from these domains
      * @param string[] $sources               Subset of MarketingStatsInterface::SOURCES; one value narrows
      *                                        to that source, none or both mean all Email Marketing traffic
      * @param string[] $emailServiceProviders Only traffic to these email service providers (e.g. "Google")
diff --git a/src/DTO/Request/Sandbox.php b/src/DTO/Request/Sandbox.php
new file mode 100644
index 0000000..73d92db
--- /dev/null
+++ b/src/DTO/Request/Sandbox.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\DTO\Request;
+
+/**
+ * Class Sandbox
+ */
+class Sandbox implements RequestInterface
+{
+    public function __construct(private ?string $name = null, private ?string $emailUsername = null)
+    {
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getName(): ?string
+    {
+        return $this->name;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getEmailUsername(): ?string
+    {
+        return $this->emailUsername;
+    }
+
+    public function toArray(): array
+    {
+        $array = [];
+
+        if (!empty($this->getName())) {
+            $array['name'] = $this->getName();
+        }
+
+        if (!empty($this->getEmailUsername())) {
+            $array['email_username'] = $this->getEmailUsername();
+        }
+
+        return $array;
+    }
+}
diff --git a/src/DTO/Request/TrackingOptOut/CreateTrackingOptOut.php b/src/DTO/Request/TrackingOptOut/CreateTrackingOptOut.php
index 4b4ea9b..eef886d 100644
--- a/src/DTO/Request/TrackingOptOut/CreateTrackingOptOut.php
+++ b/src/DTO/Request/TrackingOptOut/CreateTrackingOptOut.php
@@ -7,13 +7,13 @@
 /**
  * Class CreateTrackingOptOut
  *
- * Adds an email address to the tracking opt-out list for a sending domain.
+ * Adds an email address to the tracking opt-out list for a domain.
  */
 final class CreateTrackingOptOut implements TrackingOptOutInterface
 {
     /**
      * @param string $email    Email address to opt out of tracking
-     * @param int    $domainId ID of the sending domain the opt-out applies to
+     * @param int    $domainId ID of the domain the opt-out applies to
      */
     public function __construct(
         private string $email,
diff --git a/src/Helper/Deprecation.php b/src/Helper/Deprecation.php
new file mode 100644
index 0000000..5ebca66
--- /dev/null
+++ b/src/Helper/Deprecation.php
@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\Helper;
+
+use Mailtrap\Exception\InvalidArgumentException;
+
+/**
+ * Triggers silenced E_USER_DEPRECATED notices for renamed SDK names, once per process for each old name.
+ * Framework error handlers (Symfony, Laravel) log silenced deprecations; plain PHP ignores them.
+ *
+ * @internal
+ */
+final class Deprecation
+{
+    /**
+     * @var array<string, true>
+     */
+    private static array $triggered = [];
+
+    public static function trigger(string $old, string $new): void
+    {
+        if (isset(self::$triggered[$old])) {
+            return;
+        }
+        self::$triggered[$old] = true;
+
+        @trigger_error(
+            sprintf('%s is deprecated and will be removed in a future major release; use %s instead.', $old, $new),
+            E_USER_DEPRECATED
+        );
+    }
+
+    /**
+     * Resolves an argument renamed from $oldName to $newName, which callers may still pass by its old name.
+     * Passing both names with different values is an error.
+     */
+    public static function renamedArgument(
+        string $function,
+        string $oldName,
+        string $newName,
+        mixed $oldValue,
+        mixed $newValue,
+    ): mixed {
+        if (null === $oldValue) {
+            return $newValue;
+        }
+
+        self::trigger(sprintf('The $%s argument of %s', $oldName, $function), sprintf('$%s', $newName));
+
+        if (null !== $newValue && $newValue !== $oldValue) {
+            throw new InvalidArgumentException(
+                sprintf('%s received different values for $%s and $%s; pass only $%s.', $function, $newName, $oldName, $newName)
+            );
+        }
+
+        return $oldValue;
+    }
+
+    /**
+     * Forgets which notices were triggered, so tests can assert each one.
+     */
+    public static function reset(): void
+    {
+        self::$triggered = [];
+    }
+}
diff --git a/src/MailtrapClient.php b/src/MailtrapClient.php
index 3e56d13..2ea6407 100644
--- a/src/MailtrapClient.php
+++ b/src/MailtrapClient.php
@@ -6,6 +6,7 @@
 
 use Mailtrap\Api\EmailsSendApiInterface;
 use Mailtrap\Exception\InvalidArgumentException;
+use Mailtrap\Helper\Deprecation;
 
 /**
  * The main entry point to use all possible API layers
@@ -34,12 +35,24 @@ class MailtrapClient extends AbstractMailtrapClient
         self::LAYER_INBOUND => MailtrapInboundClient::class,
     ];
 
+    /**
+     * @param int|null $sandboxId required for the sandbox API
+     * @param int|null $inboxId   deprecated, use $sandboxId instead
+     */
     public static function initSendingEmails(
         string $apiKey,
         bool $isBulk = false,
         bool $isSandbox = false,
+        ?int $sandboxId = null,
         ?int $inboxId = null,
     ): EmailsSendApiInterface {
+        $sandboxId = Deprecation::renamedArgument(
+            self::class . '::initSendingEmails()',
+            'inboxId',
+            'sandboxId',
+            $inboxId,
+            $sandboxId
+        );
         $client = new self(new Config($apiKey));
 
         if ($isBulk && $isSandbox) {
@@ -47,7 +60,7 @@ public static function initSendingEmails(
         }
 
         if ($isSandbox) {
-            return $client->sandbox()->emails($inboxId);
+            return $client->sandbox()->emails($sandboxId);
         }
 
         if ($isBulk) {
diff --git a/src/MailtrapSandboxClient.php b/src/MailtrapSandboxClient.php
index 7194bc6..287cced 100644
--- a/src/MailtrapSandboxClient.php
+++ b/src/MailtrapSandboxClient.php
@@ -5,11 +5,12 @@
 namespace Mailtrap;
 
 /**
- * @method  Api\Sandbox\Emails      emails(int $inboxId)
+ * @method  Api\Sandbox\Emails      emails(int|null $sandboxId = null, int|null $inboxId = null) inboxId is deprecated, use sandboxId.
  * @method  Api\Sandbox\Project     projects(int $accountId)
- * @method  Api\Sandbox\Inbox       inboxes(int $accountId)
- * @method  Api\Sandbox\Attachment  attachments(int $accountId, int $inboxId)
- * @method  Api\Sandbox\Message     messages(int $accountId, int $inboxId)
+ * @method  Api\Sandbox\Sandbox     sandboxes(int $accountId)
+ * @method  Api\Sandbox\Attachment  attachments(int $accountId, int|null $sandboxId = null, int|null $inboxId = null) inboxId is deprecated, use sandboxId.
+ * @method  Api\Sandbox\Message     messages(int $accountId, int|null $sandboxId = null, int|null $inboxId = null) inboxId is deprecated, use sandboxId.
+ * @method  Api\Sandbox\Inbox       inboxes(int $accountId) Deprecated: use sandboxes() instead.
  *
  * Class MailtrapSandboxClient
  */
@@ -18,6 +19,7 @@ final class MailtrapSandboxClient extends AbstractMailtrapClient implements Emai
     public const API_MAPPING = [
         'emails' => Api\Sandbox\Emails::class,
         'projects' => Api\Sandbox\Project::class,
+        'sandboxes' => Api\Sandbox\Sandbox::class,
         'inboxes' => Api\Sandbox\Inbox::class,
         'attachments' => Api\Sandbox\Attachment::class,
         'messages' => Api\Sandbox\Message::class,
diff --git a/tests/Api/Sandbox/AttachmentTest.php b/tests/Api/Sandbox/AttachmentTest.php
index 92a3a38..6e763b9 100644
--- a/tests/Api/Sandbox/AttachmentTest.php
+++ b/tests/Api/Sandbox/AttachmentTest.php
@@ -27,7 +27,7 @@ protected function setUp(): void
 
         $this->attachment = $this->getMockBuilder(Attachment::class)
             ->onlyMethods(['httpGet'])
-            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_INBOX_ID])
+            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_SANDBOX_ID])
             ->getMock()
         ;
     }
@@ -49,7 +49,7 @@ public function testGetMessageAttachments(): void
                     '%s/api/accounts/%s/inboxes/%s/messages/%s/attachments',
                     AbstractApi::DEFAULT_HOST,
                     self::FAKE_ACCOUNT_ID,
-                    self::FAKE_INBOX_ID,
+                    self::FAKE_SANDBOX_ID,
                     self::FAKE_MESSAGE_ID,
                 ),
                 [
@@ -77,7 +77,7 @@ public function testGetMessageAttachment(): void
                 '%s/api/accounts/%s/inboxes/%s/messages/%s/attachments/%s',
                 AbstractApi::DEFAULT_HOST,
                 self::FAKE_ACCOUNT_ID,
-                self::FAKE_INBOX_ID,
+                self::FAKE_SANDBOX_ID,
                 self::FAKE_MESSAGE_ID,
                 self::FAKE_MESSAGE_ATTACHMENT_ID
             ))
diff --git a/tests/Api/Sandbox/EmailsTest.php b/tests/Api/Sandbox/EmailsTest.php
index c57eab5..47c069f 100644
--- a/tests/Api/Sandbox/EmailsTest.php
+++ b/tests/Api/Sandbox/EmailsTest.php
@@ -33,7 +33,7 @@ protected function setUp(): void
 
         $this->email = $this->getMockBuilder(Emails::class)
             ->onlyMethods(['httpPost'])
-            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_INBOX_ID])
+            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_SANDBOX_ID])
             ->getMock()
         ;
     }
@@ -70,7 +70,7 @@ public function testValidSendToSandBox(): void
         $this->email
             ->expects($this->once())
             ->method('httpPost')
-            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_INBOX_ID, [], [
+            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_SANDBOX_ID, [], [
                 'from' => [
                     'email' => 'foo@example.com',
                     'name' => 'Ms. Foo Bar',
@@ -144,7 +144,7 @@ public function testValidSendTemplateToSandbox(): void
         $this->email
             ->expects($this->once())
             ->method('httpPost')
-            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_INBOX_ID, [], [
+            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_SANDBOX_ID, [], [
                 'from' => [
                     'email' => 'foo@example.com',
                     'name' => 'Ms. Foo Bar',
@@ -230,7 +230,7 @@ public function testValidSendTemplateToSandboxNewEmailWrapper(): void
         $this->email
             ->expects($this->once())
             ->method('httpPost')
-            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_INBOX_ID, [], [
+            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/send/' . self::FAKE_SANDBOX_ID, [], [
                 'from' => [
                     'email' => 'foo@example.com',
                     'name' => 'Ms. Foo Bar',
@@ -335,7 +335,7 @@ public function testBatchSend(): void
         $this->email
             ->expects($this->once())
             ->method('httpPost')
-            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/batch/' . self::FAKE_INBOX_ID, [], $expectedPayload)
+            ->with(AbstractApi::SENDMAIL_SANDBOX_HOST . '/api/batch/' . self::FAKE_SANDBOX_ID, [], $expectedPayload)
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedResponse)));
 
         $response = $this->email->batchSend($recipientEmails, $baseEmail);
diff --git a/tests/Api/Sandbox/InboxTest.php b/tests/Api/Sandbox/InboxTest.php
index 5cbbb0e..a5997c6 100644
--- a/tests/Api/Sandbox/InboxTest.php
+++ b/tests/Api/Sandbox/InboxTest.php
@@ -1,33 +1,37 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Mailtrap\Tests\Api\Sandbox;
 
 use Mailtrap\Api\AbstractApi;
 use Mailtrap\Api\Sandbox\Inbox;
+use Mailtrap\Api\Sandbox\Sandbox;
 use Mailtrap\DTO\Request\Inbox as InboxRequest;
-use Mailtrap\Exception\HttpClientException;
-use Mailtrap\Helper\ResponseHelper;
+use Mailtrap\DTO\Request\Sandbox as SandboxRequest;
+use Mailtrap\Tests\AssertsDeprecationsTrait;
 use Mailtrap\Tests\MailtrapTestCase;
 use Nyholm\Psr7\Response;
 
 /**
+ * Backward compatibility of the deprecated Inbox API and request, replaced by Sandbox.
+ *
  * @covers Inbox
  *
  * Class InboxTest
  */
 class InboxTest extends MailtrapTestCase
 {
-    /**
-     * @var Inbox
-     */
-    private $inbox;
+    use AssertsDeprecationsTrait;
+
+    private ?Inbox $inbox;
 
     protected function setUp(): void
     {
         parent::setUp();
 
         $this->inbox = $this->getMockBuilder(Inbox::class)
-            ->onlyMethods(['httpGet', 'httpPost',  'httpPatch', 'httpDelete'])
+            ->onlyMethods(['httpGet', 'httpPost', 'httpPatch', 'httpDelete'])
             ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID])
             ->getMock()
         ;
@@ -40,377 +44,92 @@ protected function tearDown(): void
         parent::tearDown();
     }
 
-    public function testGetList(): void
+    public function testConstructorIsDeprecated(): void
     {
-        $this->inbox->expects($this->once())
-            ->method('httpGet')
-            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes')
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedInboxData())));
-
-        $response = $this->inbox->getList();
-        $responseData = ResponseHelper::toArray($response);
+        $inbox = $this->assertDeprecationTriggered(
+            'Mailtrap\Api\Sandbox\Inbox (MailtrapSandboxClient::inboxes()) is deprecated and will be removed in a future major release; use Mailtrap\Api\Sandbox\Sandbox (MailtrapSandboxClient::sandboxes()) instead.',
+            fn () => new Inbox($this->getConfigMock(), self::FAKE_ACCOUNT_ID)
+        );
 
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertCount(2, $responseData);
-        $this->assertArrayHasKey('id', array_shift($responseData));
+        $this->assertInstanceOf(Sandbox::class, $inbox);
+        $this->assertSame(self::FAKE_ACCOUNT_ID, $inbox->getAccountId());
     }
 
     public function testGetInboxAttributes(): void
     {
         $this->inbox->expects($this->once())
             ->method('httpGet')
-            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID)
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedInboxData()[0])));
+            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID)
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode(['id' => self::FAKE_SANDBOX_ID])));
 
-        $response = $this->inbox->getInboxAttributes(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
+        $response = $this->assertDeprecationTriggered(
+            'Inbox::getInboxAttributes() is deprecated and will be removed in a future major release; use Mailtrap\Api\Sandbox\Sandbox::getSandboxAttributes() instead.',
+            fn () => $this->inbox->getInboxAttributes(self::FAKE_SANDBOX_ID)
+        );
 
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-        $this->assertEquals('Admin Inbox', $responseData['name']);
-        $this->assertCount(4, $responseData['permissions']);
+        $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testValidCreate(): void
+    public function testCreateKeepsOldNamedArguments(): void
     {
-        $expectedData = [
-            "id" => self::FAKE_INBOX_ID,
-            "name" => "My new inbox",
-            "username" => "24a5f9a9947fc7",
-            "password" => "a41e3846e78543",
-            "max_size" => 600,
-            "status" => "active",
-            "email_username" => "d008137b46-4d932f",
-            "email_username_enabled" => false,
-            "sent_messages_count" => 0,
-            "forwarded_messages_count" => 0,
-            "used" => false,
-            "forward_from_email_address" => "a3336-i3866@forward.mailtrap.info",
-            "project_id" => 2424,
-            "domain" => "localhost",
-            "pop3_domain" => "localhost",
-            "email_domain" => "localhost",
-            "emails_count" => 0,
-            "emails_unread_count" => 0,
-            "last_message_sent_at" => null,
-            "smtp_ports" => [
-                25,
-                465,
-                587,
-                2525
-            ],
-            "pop3_ports" => [
-                1100,
-                9950
-            ],
-            "max_message_size" => 15728640,
-            "permissions" => [
-                "can_read" => true,
-                "can_update" => true,
-                "can_destroy" => true,
-                "can_leave" => false
-            ]
-        ];
-
         $this->inbox->expects($this->once())
             ->method('httpPost')
             ->with(
                 AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/projects/' . self::FAKE_PROJECT_ID . '/inboxes',
                 [],
-                ['inbox' => ['name' => $expectedData['name']]]
+                ['inbox' => ['name' => 'My new inbox']]
             )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode(['id' => self::FAKE_SANDBOX_ID])));
 
-        $response = $this->inbox->create(self::FAKE_PROJECT_ID, $expectedData['name']);
-        $responseData = ResponseHelper::toArray($response);
+        $response = $this->inbox->create(projectId: self::FAKE_PROJECT_ID, inboxName: 'My new inbox');
 
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
+        $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testInvalidCreate(): void
+    public function testUpdateKeepsOldNamedArgumentsAndAcceptsInboxRequest(): void
     {
-        $errorMsg = [
-            "error" => [
-                "name" => [
-                    "can't be blank",
-                ]
-            ]
-        ];
-        $this->inbox->expects($this->once())
-            ->method('httpPost')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/projects/' . self::FAKE_PROJECT_ID . '/inboxes',
-            )
-            ->willReturn(new Response(422, ['Content-Type' => 'application/json'], json_encode($errorMsg)));
-
-        $this->expectException(HttpClientException::class);
-        $this->expectExceptionMessage(
-            'Errors: name -> can\'t be blank.'
+        $inboxRequest = $this->assertDeprecationTriggered(
+            'Mailtrap\DTO\Request\Inbox is deprecated and will be removed in a future major release; use Mailtrap\DTO\Request\Sandbox instead.',
+            fn () => new InboxRequest('New inbox name', 'new-email-username')
         );
-
-        $this->inbox->create(self::FAKE_PROJECT_ID, 'a');
-    }
-
-    public function testValidDelete(): void
-    {
-        $this->inbox->expects($this->once())
-            ->method('httpDelete')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedInboxData()[0])));
-
-        $response = $this->inbox->delete(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
-
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-    }
-
-    public function testUpdate(): void
-    {
-        $newName = 'New inbox name';
-        $emailUsername = 'new-email-username';
-        $inboxRequest = new InboxRequest($newName, $emailUsername);
-        $expectedData = [
-            "id" => self::FAKE_INBOX_ID,
-            "name" => $newName,
-            "username" => "24a5f9a9947fc7",
-            "password" => "a41e3846e78543",
-            "max_size" => 600,
-            "status" => "active",
-            "email_username" => $emailUsername,
-            "email_username_enabled" => false,
-            "sent_messages_count" => 0,
-            "forwarded_messages_count" => 0,
-            "used" => false,
-            "forward_from_email_address" => "a3336-i3866@forward.mailtrap.info",
-            "project_id" => 2424,
-            "domain" => "localhost",
-            "pop3_domain" => "localhost",
-            "email_domain" => "localhost",
-            "emails_count" => 0,
-            "emails_unread_count" => 0,
-            "last_message_sent_at" => null,
-            "smtp_ports" => [
-                25,
-                465,
-                587,
-                2525
-            ],
-            "pop3_ports" => [
-                1100,
-                9950
-            ],
-            "max_message_size" => 15728640,
-            "permissions" => [
-                "can_read" => true,
-                "can_update" => true,
-                "can_destroy" => true,
-                "can_leave" => false
-            ]
-        ];
+        $this->assertInstanceOf(SandboxRequest::class, $inboxRequest);
 
         $this->inbox->expects($this->once())
             ->method('httpPatch')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID,
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID,
                 [],
-                ['inbox' => $inboxRequest->toArray()]
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
-
-        $response = $this->inbox->update(self::FAKE_INBOX_ID, $inboxRequest);
-        $responseData = ResponseHelper::toArray($response);
-
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-        $this->assertEquals($newName, $responseData['name']);
-        $this->assertEquals($emailUsername, $responseData['email_username']);
-    }
-
-    public function testClean(): void
-    {
-        $this->inbox->expects($this->once())
-            ->method('httpPatch')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/clean',
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedInboxData()[0])));
-
-        $response = $this->inbox->clean(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
-
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-    }
-
-    public function testMarkAsRead(): void
-    {
-        $this->inbox->expects($this->once())
-            ->method('httpPatch')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/all_read',
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedInboxData()[0])));
-
-        $response = $this->inbox->markAsRead(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
-
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-    }
-
-    public function testResetSmtpCredentials(): void
-    {
-        $expectedData = $this->getExpectedInboxData()[0];
-        $expectedData['username'] = 'new_username';
-        $expectedData['password'] = 'new_password';
-        $this->inbox->expects($this->once())
-            ->method('httpPatch')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/reset_credentials',
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
-
-        $response = $this->inbox->resetSmtpCredentials(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
-
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-        $this->assertEquals($expectedData['username'], $responseData['username']);
-        $this->assertEquals($expectedData['password'], $responseData['password']);
-    }
-
-    public function testToggleEmailAddress(): void
-    {
-        $expectedData = $this->getExpectedInboxData()[0];
-        $expectedData['email_username_enabled'] = true;
-
-        $this->inbox->expects($this->once())
-            ->method('httpPatch')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/toggle_email_username',
+                ['inbox' => ['name' => 'New inbox name', 'email_username' => 'new-email-username']]
             )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode(['id' => self::FAKE_SANDBOX_ID])));
 
-        $response = $this->inbox->toggleEmailAddress(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
+        $response = $this->inbox->update(inboxId: self::FAKE_SANDBOX_ID, updateInbox: $inboxRequest);
 
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-        $this->assertEquals($expectedData['email_username_enabled'], $responseData['email_username_enabled']);
+        $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testResetEmailAddress(): void
+    /**
+     * @dataProvider inboxIdMethodsProvider
+     */
+    public function testMethodsKeepOldInboxIdNamedArgument(string $method, string $httpMethod, string $pathSuffix): void
     {
-        $expectedData = $this->getExpectedInboxData()[0];
-        $expectedData['email_username'] = 'new_email_username';
-
         $this->inbox->expects($this->once())
-            ->method('httpPatch')
-            ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/reset_email_username',
-            )
-            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+            ->method($httpMethod)
+            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . $pathSuffix)
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode(['id' => self::FAKE_SANDBOX_ID])));
 
-        $response = $this->inbox->resetEmailAddress(self::FAKE_INBOX_ID);
-        $responseData = ResponseHelper::toArray($response);
+        $response = $this->inbox->{$method}(inboxId: self::FAKE_SANDBOX_ID);
 
-        $this->assertInstanceOf(Response::class, $response);
-        $this->assertArrayHasKey('id', $responseData);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['id']);
-        $this->assertEquals($expectedData['email_username'], $responseData['email_username']);
+        $this->assertSame(200, $response->getStatusCode());
     }
 
-    private function getExpectedInboxData(): array
+    public function inboxIdMethodsProvider(): iterable
     {
-        return [
-            [
-                "id" => self::FAKE_INBOX_ID,
-                "name" => "Admin Inbox",
-                "username" => "b3a87978452ae1",
-                "password" => "6be9fcfc613a7c",
-                "max_size" => 0,
-                "status" => "active",
-                "email_username" => "b7eae548c3-54c542",
-                "email_username_enabled" => false,
-                "sent_messages_count" => 52,
-                "forwarded_messages_count" => 0,
-                "used" => false,
-                "forward_from_email_address" => "a3538-i4088@forward.mailtrap.info",
-                "project_id" => 2293,
-                "domain" => "localhost",
-                "pop3_domain" => "localhost",
-                "email_domain" => "localhost",
-                "emails_count" => 0,
-                "emails_unread_count" => 0,
-                "last_message_sent_at" => null,
-                "smtp_ports" => [
-                    25,
-                    465,
-                    587,
-                    2525
-                ],
-                "pop3_ports" => [
-                    1100,
-                    9950
-                ],
-                "max_message_size" => 5242880,
-                "permissions" => [
-                    "can_read" => true,
-                    "can_update" => true,
-                    "can_destroy" => true,
-                    "can_leave" => true
-                ]
-            ],
-            [
-                "id" => 4089,
-                "name" => "Viewer Inbox",
-                "username" => "1d0aa0282f7712",
-                "password" => "5667a20f611ae7",
-                "max_size" => 0,
-                "status" => "active",
-                "email_username" => "f25402f8df-b77899",
-                "email_username_enabled" => false,
-                "sent_messages_count" => 527,
-                "forwarded_messages_count" => 0,
-                "used" => false,
-                "forward_from_email_address" => "a3538-i4089@forward.mailtrap.info",
-                "project_id" => 2293,
-                "domain" => "localhost",
-                "pop3_domain" => "localhost",
-                "email_domain" => "localhost",
-                "emails_count" => 0,
-                "emails_unread_count" => 0,
-                "last_message_sent_at" => null,
-                "smtp_ports" => [
-                    25,
-                    465,
-                    587,
-                    2525
-                ],
-                "pop3_ports" => [
-                    1100,
-                    9950
-                ],
-                "max_message_size" => 5242880,
-                "permissions" => [
-                    "can_read" => true,
-                    "can_update" => false,
-                    "can_destroy" => false,
-                    "can_leave" => true
-                ]
-            ]
-        ];
+        yield ['delete', 'httpDelete', ''];
+        yield ['clean', 'httpPatch', '/clean'];
+        yield ['markAsRead', 'httpPatch', '/all_read'];
+        yield ['resetSmtpCredentials', 'httpPatch', '/reset_credentials'];
+        yield ['toggleEmailAddress', 'httpPatch', '/toggle_email_username'];
+        yield ['resetEmailAddress', 'httpPatch', '/reset_email_username'];
     }
 }
diff --git a/tests/Api/Sandbox/MessageTest.php b/tests/Api/Sandbox/MessageTest.php
index 4787834..9a4c890 100644
--- a/tests/Api/Sandbox/MessageTest.php
+++ b/tests/Api/Sandbox/MessageTest.php
@@ -28,7 +28,7 @@ protected function setUp(): void
 
         $this->message = $this->getMockBuilder(Message::class)
             ->onlyMethods(['httpGet', 'httpPost', 'httpPatch', 'httpDelete'])
-            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_INBOX_ID])
+            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_SANDBOX_ID])
             ->getMock()
         ;
     }
@@ -45,7 +45,7 @@ public function testValidGetList(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getMessagesData())));
 
@@ -66,7 +66,7 @@ public function testValidGetListWithFilters(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages',
                 [
                     'page' => $page,
                     'search' => $search,
@@ -86,7 +86,7 @@ public function testValidGetListWithFilters(): void
         $responseData = array_shift($responseData);
         $this->assertArrayHasKey('id', $responseData);
         $this->assertEquals(self::FAKE_MESSAGE_ID, $responseData['id']);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['inbox_id']);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['inbox_id']);
     }
 
     public function testGetById(): void
@@ -94,7 +94,7 @@ public function testGetById(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getMessagesData()[0])));
 
@@ -104,7 +104,7 @@ public function testGetById(): void
         $this->assertInstanceOf(Response::class, $response);
         $this->assertArrayHasKey('id', $responseData);
         $this->assertEquals(self::FAKE_MESSAGE_ID, $responseData['id']);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['inbox_id']);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['inbox_id']);
     }
 
     /**
@@ -115,7 +115,7 @@ public function testGetSpamScore($expectedData): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/spam_report',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/spam_report',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
 
@@ -134,7 +134,7 @@ public function testGetHtmlAnalysis($expectedData): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/analyze',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/analyze',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
 
@@ -158,7 +158,7 @@ public function testGetMailHeaders(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/mail_headers',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/mail_headers',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedHeaders)));
 
@@ -176,7 +176,7 @@ public function testForward(): void
         $this->message->expects($this->once())
             ->method('httpPost')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/forward',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/forward',
                 [],
                 ['email' => $email]
             )
@@ -195,7 +195,7 @@ public function testForwardFailsWithUnverifiedRecipient(): void
         $this->message->expects($this->once())
             ->method('httpPost')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/forward',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/forward',
                 [],
                 ['email' => $email]
             )
@@ -225,7 +225,7 @@ public function testGetText(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.txt',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.txt',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'text/plain'], $expectedData));
 
@@ -242,7 +242,7 @@ public function testGetRaw(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.raw',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.raw',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'text/plain'], $expectedData));
 
@@ -259,7 +259,7 @@ public function testGetHtml(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.html',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.html',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'text/html'], $expectedData));
 
@@ -276,7 +276,7 @@ public function testGetEml(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.eml',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.eml',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'message/rfc822'], $expectedData));
 
@@ -293,7 +293,7 @@ public function testGeSource(): void
         $this->message->expects($this->once())
             ->method('httpGet')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.htmlsource',
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID . '/body.htmlsource',
             )
             ->willReturn(new Response(200, ['Content-Type' => 'text/html'], $expectedData));
 
@@ -312,7 +312,7 @@ public function testMarkAsRead($expectedData, $isRead): void
         $this->message->expects($this->once())
             ->method('httpPatch')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
                 [],
                 [
                     'message' => [
@@ -335,7 +335,7 @@ public function testDelete(): void
         $this->message->expects($this->once())
             ->method('httpDelete')
             ->with(
-                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_INBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/messages/' . self::FAKE_MESSAGE_ID,
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getMessagesData()[0])));
 
@@ -345,7 +345,7 @@ public function testDelete(): void
         $this->assertInstanceOf(Response::class, $response);
         $this->assertArrayHasKey('id', $responseData);
         $this->assertEquals(self::FAKE_MESSAGE_ID, $responseData['id']);
-        $this->assertEquals(self::FAKE_INBOX_ID, $responseData['inbox_id']);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['inbox_id']);
     }
 
     public function spamScoreProvider(): array
@@ -443,7 +443,7 @@ private function getMessagesData(): array
         return [
             [
                 "id" => self::FAKE_MESSAGE_ID,
-                "inbox_id" => self::FAKE_INBOX_ID,
+                "inbox_id" => self::FAKE_SANDBOX_ID,
                 "subject" => "Test email",
                 "sent_at" => "2022-08-19T11:34:33.839Z",
                 "from_email" => "per667son25@feeney.biz",
diff --git a/tests/Api/Sandbox/SandboxTest.php b/tests/Api/Sandbox/SandboxTest.php
new file mode 100644
index 0000000..41abb45
--- /dev/null
+++ b/tests/Api/Sandbox/SandboxTest.php
@@ -0,0 +1,416 @@
+<?php
+
+namespace Mailtrap\Tests\Api\Sandbox;
+
+use Mailtrap\Api\AbstractApi;
+use Mailtrap\Api\Sandbox\Sandbox;
+use Mailtrap\DTO\Request\Sandbox as SandboxRequest;
+use Mailtrap\Exception\HttpClientException;
+use Mailtrap\Helper\ResponseHelper;
+use Mailtrap\Tests\MailtrapTestCase;
+use Nyholm\Psr7\Response;
+
+/**
+ * @covers Sandbox
+ *
+ * Class SandboxTest
+ */
+class SandboxTest extends MailtrapTestCase
+{
+    /**
+     * @var Sandbox
+     */
+    private $sandbox;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->sandbox = $this->getMockBuilder(Sandbox::class)
+            ->onlyMethods(['httpGet', 'httpPost',  'httpPatch', 'httpDelete'])
+            ->setConstructorArgs([$this->getConfigMock(), self::FAKE_ACCOUNT_ID])
+            ->getMock()
+        ;
+    }
+
+    protected function tearDown(): void
+    {
+        $this->sandbox = null;
+
+        parent::tearDown();
+    }
+
+    public function testGetList(): void
+    {
+        $this->sandbox->expects($this->once())
+            ->method('httpGet')
+            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes')
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedSandboxData())));
+
+        $response = $this->sandbox->getList();
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertCount(2, $responseData);
+        $this->assertArrayHasKey('id', array_shift($responseData));
+    }
+
+    public function testGetSandboxAttributes(): void
+    {
+        $this->sandbox->expects($this->once())
+            ->method('httpGet')
+            ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID)
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedSandboxData()[0])));
+
+        $response = $this->sandbox->getSandboxAttributes(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+        $this->assertEquals('Admin Inbox', $responseData['name']);
+        $this->assertCount(4, $responseData['permissions']);
+    }
+
+    public function testValidCreate(): void
+    {
+        $expectedData = [
+            "id" => self::FAKE_SANDBOX_ID,
+            "name" => "My new sandbox",
+            "username" => "24a5f9a9947fc7",
+            "password" => "a41e3846e78543",
+            "max_size" => 600,
+            "status" => "active",
+            "email_username" => "d008137b46-4d932f",
+            "email_username_enabled" => false,
+            "sent_messages_count" => 0,
+            "forwarded_messages_count" => 0,
+            "used" => false,
+            "forward_from_email_address" => "a3336-i3866@forward.mailtrap.info",
+            "project_id" => 2424,
+            "domain" => "localhost",
+            "pop3_domain" => "localhost",
+            "email_domain" => "localhost",
+            "emails_count" => 0,
+            "emails_unread_count" => 0,
+            "last_message_sent_at" => null,
+            "smtp_ports" => [
+                25,
+                465,
+                587,
+                2525
+            ],
+            "pop3_ports" => [
+                1100,
+                9950
+            ],
+            "max_message_size" => 15728640,
+            "permissions" => [
+                "can_read" => true,
+                "can_update" => true,
+                "can_destroy" => true,
+                "can_leave" => false
+            ]
+        ];
+
+        $this->sandbox->expects($this->once())
+            ->method('httpPost')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/projects/' . self::FAKE_PROJECT_ID . '/inboxes',
+                [],
+                ['inbox' => ['name' => $expectedData['name']]]
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+
+        $response = $this->sandbox->create(self::FAKE_PROJECT_ID, $expectedData['name']);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+    }
+
+    public function testInvalidCreate(): void
+    {
+        $errorMsg = [
+            "error" => [
+                "name" => [
+                    "can't be blank",
+                ]
+            ]
+        ];
+        $this->sandbox->expects($this->once())
+            ->method('httpPost')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/projects/' . self::FAKE_PROJECT_ID . '/inboxes',
+            )
+            ->willReturn(new Response(422, ['Content-Type' => 'application/json'], json_encode($errorMsg)));
+
+        $this->expectException(HttpClientException::class);
+        $this->expectExceptionMessage(
+            'Errors: name -> can\'t be blank.'
+        );
+
+        $this->sandbox->create(self::FAKE_PROJECT_ID, 'a');
+    }
+
+    public function testValidDelete(): void
+    {
+        $this->sandbox->expects($this->once())
+            ->method('httpDelete')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedSandboxData()[0])));
+
+        $response = $this->sandbox->delete(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+    }
+
+    public function testUpdate(): void
+    {
+        $newName = 'New sandbox name';
+        $emailUsername = 'new-email-username';
+        $sandboxRequest = new SandboxRequest($newName, $emailUsername);
+        $expectedData = [
+            "id" => self::FAKE_SANDBOX_ID,
+            "name" => $newName,
+            "username" => "24a5f9a9947fc7",
+            "password" => "a41e3846e78543",
+            "max_size" => 600,
+            "status" => "active",
+            "email_username" => $emailUsername,
+            "email_username_enabled" => false,
+            "sent_messages_count" => 0,
+            "forwarded_messages_count" => 0,
+            "used" => false,
+            "forward_from_email_address" => "a3336-i3866@forward.mailtrap.info",
+            "project_id" => 2424,
+            "domain" => "localhost",
+            "pop3_domain" => "localhost",
+            "email_domain" => "localhost",
+            "emails_count" => 0,
+            "emails_unread_count" => 0,
+            "last_message_sent_at" => null,
+            "smtp_ports" => [
+                25,
+                465,
+                587,
+                2525
+            ],
+            "pop3_ports" => [
+                1100,
+                9950
+            ],
+            "max_message_size" => 15728640,
+            "permissions" => [
+                "can_read" => true,
+                "can_update" => true,
+                "can_destroy" => true,
+                "can_leave" => false
+            ]
+        ];
+
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID,
+                [],
+                ['inbox' => $sandboxRequest->toArray()]
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+
+        $response = $this->sandbox->update(self::FAKE_SANDBOX_ID, $sandboxRequest);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+        $this->assertEquals($newName, $responseData['name']);
+        $this->assertEquals($emailUsername, $responseData['email_username']);
+    }
+
+    public function testClean(): void
+    {
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/clean',
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedSandboxData()[0])));
+
+        $response = $this->sandbox->clean(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+    }
+
+    public function testMarkAsRead(): void
+    {
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/all_read',
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($this->getExpectedSandboxData()[0])));
+
+        $response = $this->sandbox->markAsRead(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+    }
+
+    public function testResetSmtpCredentials(): void
+    {
+        $expectedData = $this->getExpectedSandboxData()[0];
+        $expectedData['username'] = 'new_username';
+        $expectedData['password'] = 'new_password';
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/reset_credentials',
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+
+        $response = $this->sandbox->resetSmtpCredentials(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+        $this->assertEquals($expectedData['username'], $responseData['username']);
+        $this->assertEquals($expectedData['password'], $responseData['password']);
+    }
+
+    public function testToggleEmailAddress(): void
+    {
+        $expectedData = $this->getExpectedSandboxData()[0];
+        $expectedData['email_username_enabled'] = true;
+
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/toggle_email_username',
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+
+        $response = $this->sandbox->toggleEmailAddress(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+        $this->assertEquals($expectedData['email_username_enabled'], $responseData['email_username_enabled']);
+    }
+
+    public function testResetEmailAddress(): void
+    {
+        $expectedData = $this->getExpectedSandboxData()[0];
+        $expectedData['email_username'] = 'new_email_username';
+
+        $this->sandbox->expects($this->once())
+            ->method('httpPatch')
+            ->with(
+                AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/inboxes/' . self::FAKE_SANDBOX_ID . '/reset_email_username',
+            )
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], json_encode($expectedData)));
+
+        $response = $this->sandbox->resetEmailAddress(self::FAKE_SANDBOX_ID);
+        $responseData = ResponseHelper::toArray($response);
+
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertArrayHasKey('id', $responseData);
+        $this->assertEquals(self::FAKE_SANDBOX_ID, $responseData['id']);
+        $this->assertEquals($expectedData['email_username'], $responseData['email_username']);
+    }
+
+    private function getExpectedSandboxData(): array
+    {
+        return [
+            [
+                "id" => self::FAKE_SANDBOX_ID,
+                "name" => "Admin Inbox",
+                "username" => "b3a87978452ae1",
+                "password" => "6be9fcfc613a7c",
+                "max_size" => 0,
+                "status" => "active",
+                "email_username" => "b7eae548c3-54c542",
+                "email_username_enabled" => false,
+                "sent_messages_count" => 52,
+                "forwarded_messages_count" => 0,
+                "used" => false,
+                "forward_from_email_address" => "a3538-i4088@forward.mailtrap.info",
+                "project_id" => 2293,
+                "domain" => "localhost",
+                "pop3_domain" => "localhost",
+                "email_domain" => "localhost",
+                "emails_count" => 0,
+                "emails_unread_count" => 0,
+                "last_message_sent_at" => null,
+                "smtp_ports" => [
+                    25,
+                    465,
+                    587,
+                    2525
+                ],
+                "pop3_ports" => [
+                    1100,
+                    9950
+                ],
+                "max_message_size" => 5242880,
+                "permissions" => [
+                    "can_read" => true,
+                    "can_update" => true,
+                    "can_destroy" => true,
+                    "can_leave" => true
+                ]
+            ],
+            [
+                "id" => 4089,
+                "name" => "Viewer Inbox",
+                "username" => "1d0aa0282f7712",
+                "password" => "5667a20f611ae7",
+                "max_size" => 0,
+                "status" => "active",
+                "email_username" => "f25402f8df-b77899",
+                "email_username_enabled" => false,
+                "sent_messages_count" => 527,
+                "forwarded_messages_count" => 0,
+                "used" => false,
+                "forward_from_email_address" => "a3538-i4089@forward.mailtrap.info",
+                "project_id" => 2293,
+                "domain" => "localhost",
+                "pop3_domain" => "localhost",
+                "email_domain" => "localhost",
+                "emails_count" => 0,
+                "emails_unread_count" => 0,
+                "last_message_sent_at" => null,
+                "smtp_ports" => [
+                    25,
+                    465,
+                    587,
+                    2525
+                ],
+                "pop3_ports" => [
+                    1100,
+                    9950
+                ],
+                "max_message_size" => 5242880,
+                "permissions" => [
+                    "can_read" => true,
+                    "can_update" => false,
+                    "can_destroy" => false,
+                    "can_leave" => true
+                ]
+            ]
+        ];
+    }
+}
diff --git a/tests/Api/Sending/DomainTest.php b/tests/Api/Sending/DomainTest.php
index 8f7d2ec..c4c0f26 100644
--- a/tests/Api/Sending/DomainTest.php
+++ b/tests/Api/Sending/DomainTest.php
@@ -10,6 +10,7 @@
 use Mailtrap\Exception\HttpClientException;
 use Mailtrap\Exception\InvalidArgumentException;
 use Mailtrap\Helper\ResponseHelper;
+use Mailtrap\Tests\AssertsDeprecationsTrait;
 use Mailtrap\Tests\MailtrapTestCase;
 use Nyholm\Psr7\Response;
 
@@ -20,6 +21,8 @@
  */
 class DomainTest extends MailtrapTestCase
 {
+    use AssertsDeprecationsTrait;
+
     private ?Domain $domain;
 
     protected function setUp(): void
@@ -37,7 +40,7 @@ protected function tearDown(): void
         parent::tearDown();
     }
 
-    public function testGetSendingDomains(): void
+    public function testGetDomains(): void
     {
         $expectedResponseBody = $this->getExpectedDomainsResponse();
 
@@ -46,7 +49,7 @@ public function testGetSendingDomains(): void
             ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/sending_domains')
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], $expectedResponseBody));
 
-        $response = $this->domain->getSendingDomains();
+        $response = $this->domain->getDomains();
         $responseData = ResponseHelper::toArray($response);
 
         $this->assertSame(200, $response->getStatusCode());
@@ -58,7 +61,7 @@ public function testGetSendingDomains(): void
         $this->assertArrayHasKey('permissions', $responseData['data'][0]);
     }
 
-    public function testCreateSendingDomain(): void
+    public function testCreateDomain(): void
     {
         $domainName = 'example.com';
         $expectedResponseBody = $this->getExpectedDomainResponse($domainName);
@@ -76,7 +79,7 @@ public function testCreateSendingDomain(): void
             )
             ->willReturn(new Response(201, ['Content-Type' => 'application/json'], $expectedResponseBody));
 
-        $response = $this->domain->createSendingDomain($domainName);
+        $response = $this->domain->createDomain($domainName);
         $responseData = ResponseHelper::toArray($response);
 
         $this->assertSame(201, $response->getStatusCode());
@@ -88,7 +91,7 @@ public function testCreateSendingDomain(): void
         $this->assertSame($domainName, $responseData['domain_name']);
     }
 
-    public function testCreateSendingDomainInvalid(): void
+    public function testCreateDomainInvalid(): void
     {
         $domainName = '';
         $errorResponse = [
@@ -115,7 +118,7 @@ public function testCreateSendingDomainInvalid(): void
         $this->expectException(HttpClientException::class);
         $this->expectExceptionMessage('Errors: sending_domain -> domain_name -> can\'t be blank.');
 
-        $this->domain->createSendingDomain($domainName);
+        $this->domain->createDomain($domainName);
     }
 
     public function testGetDomainById(): void
@@ -158,7 +161,7 @@ public function testGetDomainByIdNotFound(): void
         $this->domain->getDomainById($domainId);
     }
 
-    public function testDeleteSendingDomain(): void
+    public function testDeleteDomain(): void
     {
         $domainId = 12345;
 
@@ -167,11 +170,11 @@ public function testDeleteSendingDomain(): void
             ->with(AbstractApi::DEFAULT_HOST . '/api/accounts/' . self::FAKE_ACCOUNT_ID . '/sending_domains/' . $domainId)
             ->willReturn(new Response(204));
 
-        $response = $this->domain->deleteSendingDomain($domainId);
+        $response = $this->domain->deleteDomain($domainId);
         $this->assertSame(204, $response->getStatusCode());
     }
 
-    public function testDeleteSendingDomainNotFound(): void
+    public function testDeleteDomainNotFound(): void
     {
         $domainId = 99999;
         $errorResponse = [
@@ -186,7 +189,7 @@ public function testDeleteSendingDomainNotFound(): void
         $this->expectException(HttpClientException::class);
         $this->expectExceptionMessage('The requested entity has not been found. Errors: Domain not found.');
 
-        $this->domain->deleteSendingDomain($domainId);
+        $this->domain->deleteDomain($domainId);
     }
 
     public function testSendDomainSetupInstructions(): void
@@ -277,7 +280,7 @@ private function getExpectedDomainsResponse(): string
         ]);
     }
 
-    public function testUpdateSendingDomain(): void
+    public function testUpdateDomain(): void
     {
         $domainId = 12345;
         $expectedResponseBody = $this->getExpectedDomainResponse('example.com', $domainId);
@@ -299,7 +302,7 @@ public function testUpdateSendingDomain(): void
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], $expectedResponseBody));
 
-        $response = $this->domain->updateSendingDomain(
+        $response = $this->domain->updateDomain(
             $domainId,
             new UpdateDomain(
                 openTrackingEnabled: true,
@@ -315,7 +318,7 @@ public function testUpdateSendingDomain(): void
         $this->assertSame($domainId, $responseData['id']);
     }
 
-    public function testUpdateSendingDomainSendsOnlyProvidedFields(): void
+    public function testUpdateDomainSendsOnlyProvidedFields(): void
     {
         $domainId = 12345;
         $expectedResponseBody = $this->getExpectedDomainResponse('example.com', $domainId);
@@ -333,7 +336,7 @@ public function testUpdateSendingDomainSendsOnlyProvidedFields(): void
             )
             ->willReturn(new Response(200, ['Content-Type' => 'application/json'], $expectedResponseBody));
 
-        $response = $this->domain->updateSendingDomain(
+        $response = $this->domain->updateDomain(
             $domainId,
             new UpdateDomain(trackingOptOutEnabled: false)
         );
@@ -341,16 +344,45 @@ public function testUpdateSendingDomainSendsOnlyProvidedFields(): void
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testUpdateSendingDomainWithEmptyPayload(): void
+    public function testUpdateDomainWithEmptyPayload(): void
     {
         $this->domain->expects($this->never())->method('httpPatch');
 
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage(
-            'At least one updatable field must be provided to update a sending domain'
+            'At least one updatable field must be provided to update a domain'
         );
 
-        $this->domain->updateSendingDomain(12345, new UpdateDomain());
+        $this->domain->updateDomain(12345, new UpdateDomain());
+    }
+
+    /**
+     * @dataProvider deprecatedMethodsProvider
+     */
+    public function testDeprecatedMethods(string $method, array $arguments, string $httpMethod, string $newMethod): void
+    {
+        $this->domain->expects($this->once())
+            ->method($httpMethod)
+            ->willReturn(new Response(200, ['Content-Type' => 'application/json'], $this->getExpectedDomainResponse('example.com')));
+
+        $response = $this->assertDeprecationTriggered(
+            sprintf(
+                'Mailtrap\Api\Sending\Domain::%s() is deprecated and will be removed in a future major release; use Mailtrap\Api\Sending\Domain::%s() instead.',
+                $method,
+                $newMethod
+            ),
+            fn () => $this->domain->{$method}(...$arguments)
+        );
+
+        $this->assertSame(200, $response->getStatusCode());
+    }
+
+    public function deprecatedMethodsProvider(): iterable
+    {
+        yield ['getSendingDomains', [], 'httpGet', 'getDomains'];
+        yield ['createSendingDomain', ['example.com'], 'httpPost', 'createDomain'];
+        yield ['updateSendingDomain', [12345, new UpdateDomain(openTrackingEnabled: false)], 'httpPatch', 'updateDomain'];
+        yield ['deleteSendingDomain', [12345], 'httpDelete', 'deleteDomain'];
     }
 
     private function getExpectedDomainResponse(string $domainName, ?int $domainId = null): string
diff --git a/tests/AssertsDeprecationsTrait.php b/tests/AssertsDeprecationsTrait.php
new file mode 100644
index 0000000..47a5e09
--- /dev/null
+++ b/tests/AssertsDeprecationsTrait.php
@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\Tests;
+
+use Mailtrap\Helper\Deprecation;
+
+/**
+ * Captures the SDK's silenced E_USER_DEPRECATED notices, which PHPUnit's own error handler ignores.
+ */
+trait AssertsDeprecationsTrait
+{
+    /**
+     * Runs $call, asserts it triggered a deprecation notice containing $needle and returns what $call returned.
+     */
+    protected function assertDeprecationTriggered(string $needle, callable $call): mixed
+    {
+        [$result, $messages] = $this->captureDeprecations($call);
+
+        self::assertNotEmpty(
+            array_filter($messages, static fn (string $message): bool => str_contains($message, $needle)),
+            sprintf('No deprecation notice containing "%s" was triggered. Triggered: %s', $needle, json_encode($messages))
+        );
+
+        return $result;
+    }
+
+    /**
+     * Runs $call, asserts it triggered no deprecation notice and returns what $call returned.
+     */
+    protected function assertNoDeprecationTriggered(callable $call): mixed
+    {
+        [$result, $messages] = $this->captureDeprecations($call);
+
+        self::assertSame([], $messages, 'Unexpected deprecation notices were triggered.');
+
+        return $result;
+    }
+
+    /**
+     * Runs $call and returns what it returned and the deprecation notices it triggered.
+     *
+     * @return array{0: mixed, 1: string[]}
+     */
+    protected function captureDeprecations(callable $call): array
+    {
+        Deprecation::reset();
+        $messages = [];
+        set_error_handler(static function (int $level, string $message) use (&$messages): bool {
+            $messages[] = $message;
+
+            return true;
+        }, E_USER_DEPRECATED);
+
+        try {
+            $result = $call();
+        } finally {
+            restore_error_handler();
+        }
+
+        return [$result, $messages];
+    }
+}
diff --git a/tests/Bridge/Transport/MailtrapSdkTransportFactoryTest.php b/tests/Bridge/Transport/MailtrapSdkTransportFactoryTest.php
index ca07695..95bdc58 100644
--- a/tests/Bridge/Transport/MailtrapSdkTransportFactoryTest.php
+++ b/tests/Bridge/Transport/MailtrapSdkTransportFactoryTest.php
@@ -8,7 +8,10 @@
 use Mailtrap\Bridge\Transport\MailtrapSdkTransport;
 use Mailtrap\Bridge\Transport\MailtrapSdkTransportFactory;
 use Mailtrap\Config;
+use Mailtrap\Exception\InvalidArgumentException;
+use Mailtrap\Exception\RuntimeException;
 use Mailtrap\MailtrapClient;
+use Mailtrap\Tests\AssertsDeprecationsTrait;
 use Symfony\Component\HttpClient\Psr18Client;
 use Symfony\Component\Mailer\Transport\Dsn;
 use Symfony\Component\Mailer\Transport\TransportFactoryInterface;
@@ -20,6 +23,8 @@
  */
 class MailtrapSdkTransportFactoryTest extends TransportFactoryTestCase
 {
+    use AssertsDeprecationsTrait;
+
     protected function setUp(): void
     {
         if (!class_exists(Dsn::class)) {
@@ -58,7 +63,7 @@ public function createProvider(): iterable
         $bulkConfig = (new Config(self::USER))
             ->setHttpClient($psrClient)
             ->setHost(AbstractApi::SENDMAIL_BULK_HOST);
-        $inboxId = 1234;
+        $sandboxId = 1234;
 
         yield [
             new Dsn('mailtrap+sdk', 'default', self::USER),
@@ -82,9 +87,9 @@ public function createProvider(): iterable
 
         // sandbox
         yield [
-            new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, ['inboxId' => 1234]),
+            new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, ['sandboxId' => 1234]),
             new MailtrapSdkTransport(
-                (new MailtrapClient($sandboxConfig))->sandbox()->emails($inboxId),
+                (new MailtrapClient($sandboxConfig))->sandbox()->emails($sandboxId),
                 $sandboxConfig,
                 $dispatcher,
                 $logger
@@ -103,6 +108,90 @@ public function createProvider(): iterable
         ];
     }
 
+    public function testSandboxIdOptionTriggersNoDeprecation(): void
+    {
+        $transport = $this->assertNoDeprecationTriggered(
+            fn () => $this->getFactory()->create(
+                new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, ['sandboxId' => '1234'])
+            )
+        );
+
+        $this->assertSame(sprintf('mailtrap+sdk://%s?sandboxId=1234', AbstractApi::SENDMAIL_SANDBOX_HOST), (string) $transport);
+    }
+
+    /**
+     * @dataProvider deprecatedInboxIdOptionsProvider
+     */
+    public function testInboxIdOptionIsDeprecated(array $options): void
+    {
+        $transport = $this->assertDeprecationTriggered(
+            'The "inboxId" option of the mailtrap+sdk transport (MAILTRAP_INBOX_ID in Laravel) is deprecated and will be removed in a future major release; use the "sandboxId" option (MAILTRAP_SANDBOX_ID) instead.',
+            fn () => $this->getFactory()->create(
+                new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, $options)
+            )
+        );
+
+        $this->assertSame(sprintf('mailtrap+sdk://%s?sandboxId=1234', AbstractApi::SENDMAIL_SANDBOX_HOST), (string) $transport);
+    }
+
+    public function deprecatedInboxIdOptionsProvider(): iterable
+    {
+        // MAILER_DSN=mailtrap+sdk://APIKEY@sandbox.api.mailtrap.io?inboxId=1234
+        yield 'Symfony DSN query' => [['inboxId' => '1234']];
+
+        // Laravel passes its "services.mailtrap-sdk" config as the options: here only MAILTRAP_INBOX_ID is set
+        yield 'Laravel config' => [[
+            'host' => AbstractApi::SENDMAIL_SANDBOX_HOST,
+            'apiKey' => self::USER,
+            'sandboxId' => null,
+            'inboxId' => '1234',
+        ]];
+
+        yield 'empty sandboxId' => [['sandboxId' => '', 'inboxId' => '1234']];
+
+        yield 'sandboxId and inboxId with the same value' => [['sandboxId' => '1234', 'inboxId' => '1234']];
+    }
+
+    /**
+     * @dataProvider differentSandboxIdAndInboxIdOptionsProvider
+     */
+    public function testDifferentSandboxIdAndInboxIdOptions(array $options): void
+    {
+        $this->expectExceptionObject(new InvalidArgumentException(
+            'The mailtrap+sdk transport received different values for the "sandboxId" and "inboxId" options (MAILTRAP_SANDBOX_ID and MAILTRAP_INBOX_ID in Laravel); set only "sandboxId".'
+        ));
+
+        $this->getFactory()->create(
+            new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, $options)
+        );
+    }
+
+    public function differentSandboxIdAndInboxIdOptionsProvider(): iterable
+    {
+        yield 'two IDs' => [['sandboxId' => '1234', 'inboxId' => '5678']];
+        yield 'zero sandboxId' => [['sandboxId' => '0', 'inboxId' => '1234']];
+        yield 'zero inboxId' => [['sandboxId' => '1234', 'inboxId' => '0']];
+    }
+
+    /**
+     * @dataProvider withoutSandboxIdOptionsProvider
+     */
+    public function testSandboxWithoutSandboxIdOption(array $options): void
+    {
+        $this->expectExceptionObject(new RuntimeException(
+            'You cannot send an email to a sandbox with an empty "sandboxId" parameter. Example -> "MAILER_DSN=mailtrap+sdk://APIKEY@sandbox.api.mailtrap.io?sandboxId=1234"'
+        ));
+
+        $this->getFactory()->create(new Dsn('mailtrap+sdk', AbstractApi::SENDMAIL_SANDBOX_HOST, self::USER, null, null, $options));
+    }
+
+    public function withoutSandboxIdOptionsProvider(): iterable
+    {
+        yield 'no options' => [[]];
+        yield 'zero sandboxId' => [['sandboxId' => '0']];
+        yield 'zero inboxId' => [['inboxId' => '0']];
+    }
+
     public function unsupportedSchemeProvider(): iterable
     {
         yield [
diff --git a/tests/Bridge/Transport/MailtrapSdkTransportTest.php b/tests/Bridge/Transport/MailtrapSdkTransportTest.php
index 4fcef75..028e6c4 100644
--- a/tests/Bridge/Transport/MailtrapSdkTransportTest.php
+++ b/tests/Bridge/Transport/MailtrapSdkTransportTest.php
@@ -42,7 +42,7 @@ public static function getTransportData(): array
         $sendConfig = (new Config('key'))->setHost(AbstractApi::SENDMAIL_TRANSACTIONAL_HOST);
         $sandboxConfig = (new Config('key'))->setHost(AbstractApi::SENDMAIL_SANDBOX_HOST);
         $bulkConfig = (new Config('key'))->setHost(AbstractApi::SENDMAIL_BULK_HOST);
-        $inboxId = 1234;
+        $sandboxId = 1234;
 
         return [
             [
@@ -54,10 +54,10 @@ public static function getTransportData(): array
             ],
             [
                 new MailtrapSdkTransport(
-                    (new MailtrapSandboxClient($sandboxConfig))->emails($inboxId),
+                    (new MailtrapSandboxClient($sandboxConfig))->emails($sandboxId),
                     $sandboxConfig
                 ),
-                sprintf('mailtrap+sdk://%s?inboxId=%s', AbstractApi::SENDMAIL_SANDBOX_HOST, $inboxId),
+                sprintf('mailtrap+sdk://%s?sandboxId=%s', AbstractApi::SENDMAIL_SANDBOX_HOST, $sandboxId),
             ],
             [
                 new MailtrapSdkTransport(
diff --git a/tests/Helper/DeprecationTest.php b/tests/Helper/DeprecationTest.php
new file mode 100644
index 0000000..31ab258
--- /dev/null
+++ b/tests/Helper/DeprecationTest.php
@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailtrap\Tests\Helper;
+
+use Mailtrap\Exception\InvalidArgumentException;
+use Mailtrap\Helper\Deprecation;
+use Mailtrap\Tests\AssertsDeprecationsTrait;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \Mailtrap\Helper\Deprecation
+ *
+ * Class DeprecationTest
+ */
+class DeprecationTest extends TestCase
+{
+    use AssertsDeprecationsTrait;
+
+    public function testTriggersOncePerOldName(): void
+    {
+        [, $messages] = $this->captureDeprecations(static function (): void {
+            Deprecation::trigger('Foo::old()', 'Foo::new()');
+            Deprecation::trigger('Foo::old()', 'Foo::new()');
+            Deprecation::trigger('Bar::old()', 'Bar::new()');
+        });
+
+        $this->assertSame([
+            'Foo::old() is deprecated and will be removed in a future major release; use Foo::new() instead.',
+            'Bar::old() is deprecated and will be removed in a future major release; use Bar::new() instead.',
+        ], $messages);
+    }
+
+    public function testRenamedArgumentReturnsNewValueSilently(): void
+    {
+        $this->assertNoDeprecationTriggered(function (): void {
+            $this->assertSame(1, Deprecation::renamedArgument('foo()', 'old', 'new', null, 1));
+            $this->assertNull(Deprecation::renamedArgument('foo()', 'old', 'new', null, null));
+        });
+    }
+
+    public function testRenamedArgumentFallsBackToOldValue(): void
+    {
+        [, $messages] = $this->captureDeprecations(function (): void {
+            $this->assertSame(1, Deprecation::renamedArgument('foo()', 'old', 'new', 1, null));
+            $this->assertSame(1, Deprecation::renamedArgument('foo()', 'old', 'new', 1, 1));
+        });
+
+        $this->assertSame(
+            ['The $old argument of foo() is deprecated and will be removed in a future major release; use $new instead.'],
+            $messages
+        );
+    }
+
+    public function testRenamedArgumentRejectsDifferentValues(): void
+    {
+        $this->expectExceptionObject(
+            new InvalidArgumentException('foo() received different values for $new and $old; pass only $new.')
+        );
+
+        $this->captureDeprecations(static fn () => Deprecation::renamedArgument('foo()', 'old', 'new', 1, 2));
+    }
+}
diff --git a/tests/MailtrapClientTestCase.php b/tests/MailtrapClientTestCase.php
index 80153fa..7e985fb 100644
--- a/tests/MailtrapClientTestCase.php
+++ b/tests/MailtrapClientTestCase.php
@@ -13,7 +13,7 @@
  */
 abstract class MailtrapClientTestCase extends MailtrapTestCase
 {
-    private ?MailtrapClientInterface $mailtrapClientLayer;
+    protected ?MailtrapClientInterface $mailtrapClientLayer;
 
     abstract public function getMailtrapClientClassName(): string;
 
diff --git a/tests/MailtrapSandboxClientTest.php b/tests/MailtrapSandboxClientTest.php
index 0f72582..7adac48 100644
--- a/tests/MailtrapSandboxClientTest.php
+++ b/tests/MailtrapSandboxClientTest.php
@@ -5,7 +5,10 @@
 namespace Mailtrap\Tests;
 
 use Mailtrap\Api\Sandbox\Emails as SandboxSendingEmails;
+use Mailtrap\Api\Sandbox\Inbox;
+use Mailtrap\Api\Sandbox\Sandbox;
 use Mailtrap\Api\Sandbox\SandboxInterface;
+use Mailtrap\Exception\InvalidArgumentException;
 use Mailtrap\MailtrapClient;
 use Mailtrap\MailtrapSandboxClient;
 
@@ -16,6 +19,8 @@
  */
 class MailtrapSandboxClientTest extends MailtrapClientTestCase
 {
+    use AssertsDeprecationsTrait;
+
     public function getMailtrapClientClassName(): string
     {
         return MailtrapSandboxClient::class;
@@ -30,19 +35,125 @@ public function mapInstancesProvider(): iterable
     {
         foreach (MailtrapSandboxClient::API_MAPPING as $key => $item) {
             yield match ($key) {
-                'emails' => [new $item($this->getConfigMock(), self::FAKE_INBOX_ID)],
-                'projects', 'inboxes' => [new $item($this->getConfigMock(), self::FAKE_ACCOUNT_ID)],
-                'messages', 'attachments' => [new $item($this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_INBOX_ID)],
+                'emails' => [new $item($this->getConfigMock(), self::FAKE_SANDBOX_ID)],
+                'projects', 'sandboxes', 'inboxes' => [new $item($this->getConfigMock(), self::FAKE_ACCOUNT_ID)],
+                'messages', 'attachments' => [new $item($this->getConfigMock(), self::FAKE_ACCOUNT_ID, self::FAKE_SANDBOX_ID)],
                 default => [new $item($this->getConfigMock())],
             };
         }
     }
 
+    public function testSandboxes(): void
+    {
+        $sandboxes = $this->assertNoDeprecationTriggered(fn () => $this->mailtrapClientLayer->sandboxes(self::FAKE_ACCOUNT_ID));
+
+        $this->assertInstanceOf(Sandbox::class, $sandboxes);
+        $this->assertNotInstanceOf(Inbox::class, $sandboxes);
+        $this->assertSame(self::FAKE_ACCOUNT_ID, $sandboxes->getAccountId());
+    }
+
+    public function testInboxesIsDeprecated(): void
+    {
+        $inboxes = $this->assertDeprecationTriggered(
+            'Mailtrap\Api\Sandbox\Inbox (MailtrapSandboxClient::inboxes()) is deprecated and will be removed in a future major release; use Mailtrap\Api\Sandbox\Sandbox (MailtrapSandboxClient::sandboxes()) instead.',
+            fn () => $this->mailtrapClientLayer->inboxes(self::FAKE_ACCOUNT_ID)
+        );
+
+        $this->assertInstanceOf(Inbox::class, $inboxes);
+        $this->assertInstanceOf(Sandbox::class, $inboxes);
+        $this->assertSame(self::FAKE_ACCOUNT_ID, $inboxes->getAccountId());
+    }
+
+    /**
+     * @dataProvider sandboxIdApisProvider
+     */
+    public function testSandboxIdArgument(string $method, array $arguments): void
+    {
+        $api = $this->assertNoDeprecationTriggered(
+            fn () => $this->mailtrapClientLayer->{$method}(...$arguments, ...['sandboxId' => self::FAKE_SANDBOX_ID])
+        );
+
+        $this->assertSame(self::FAKE_SANDBOX_ID, $api->getSandboxId());
+    }
+
+    /**
+     * @dataProvider sandboxIdApisProvider
+     */
+    public function testInboxIdArgumentIsDeprecated(string $method, array $arguments, string $className): void
+    {
+        $api = $this->assertDeprecationTriggered(
+            sprintf('The $inboxId argument of %s::__construct() is deprecated', $className),
+            fn () => $this->mailtrapClientLayer->{$method}(...$arguments, ...['inboxId' => self::FAKE_SANDBOX_ID])
+        );
+
+        $this->assertSame(self::FAKE_SANDBOX_ID, $api->getSandboxId());
+    }
+
+    /**
+     * @dataProvider sandboxIdApisProvider
+     */
+    public function testGetInboxIdIsDeprecated(string $method, array $arguments, string $className): void
+    {
+        $api = $this->mailtrapClientLayer->{$method}(...$arguments, ...[self::FAKE_SANDBOX_ID]);
+
+        $inboxId = $this->assertDeprecationTriggered(
+            sprintf('%1$s::getInboxId() is deprecated and will be removed in a future major release; use %1$s::getSandboxId() instead.', $className),
+            fn () => $api->getInboxId()
+        );
+
+        $this->assertSame(self::FAKE_SANDBOX_ID, $inboxId);
+    }
+
+    /**
+     * @dataProvider sandboxIdApisProvider
+     */
+    public function testSandboxIdIsRequired(string $method, array $arguments, string $className): void
+    {
+        $this->expectExceptionObject(
+            new InvalidArgumentException(sprintf('%s::__construct() requires the $sandboxId argument.', $className))
+        );
+
+        $this->mailtrapClientLayer->{$method}(...$arguments);
+    }
+
+    /**
+     * @dataProvider sandboxIdApisProvider
+     */
+    public function testDifferentSandboxIdAndInboxIdAreRejected(string $method, array $arguments, string $className): void
+    {
+        $this->expectExceptionObject(new InvalidArgumentException(sprintf(
+            '%s::__construct() received different values for $sandboxId and $inboxId; pass only $sandboxId.',
+            $className
+        )));
+
+        $this->mailtrapClientLayer->{$method}(...$arguments, ...['sandboxId' => self::FAKE_SANDBOX_ID, 'inboxId' => self::FAKE_SANDBOX_ID + 1]);
+    }
+
+    public function sandboxIdApisProvider(): iterable
+    {
+        yield ['emails', [], SandboxSendingEmails::class];
+        yield ['messages', [self::FAKE_ACCOUNT_ID], MailtrapSandboxClient::API_MAPPING['messages']];
+        yield ['attachments', [self::FAKE_ACCOUNT_ID], MailtrapSandboxClient::API_MAPPING['attachments']];
+    }
+
     public function testValidInitSandboxSendingEmails(): void
     {
-        $this->assertInstanceOf(
-            SandboxSendingEmails::class,
-            MailtrapClient::initSendingEmails(apiKey: self::DEFAULT_API_KEY, isSandbox: true, inboxId: self::FAKE_INBOX_ID)
+        $emails = $this->assertNoDeprecationTriggered(
+            fn () => MailtrapClient::initSendingEmails(apiKey: self::DEFAULT_API_KEY, isSandbox: true, sandboxId: self::FAKE_SANDBOX_ID)
         );
+
+        $this->assertInstanceOf(SandboxSendingEmails::class, $emails);
+        $this->assertSame(self::FAKE_SANDBOX_ID, $emails->getSandboxId());
+    }
+
+    public function testInitSandboxSendingEmailsWithInboxIdIsDeprecated(): void
+    {
+        $emails = $this->assertDeprecationTriggered(
+            'The $inboxId argument of Mailtrap\MailtrapClient::initSendingEmails() is deprecated and will be removed in a future major release; use $sandboxId instead.',
+            fn () => MailtrapClient::initSendingEmails(apiKey: self::DEFAULT_API_KEY, isSandbox: true, inboxId: self::FAKE_SANDBOX_ID)
+        );
+
+        $this->assertInstanceOf(SandboxSendingEmails::class, $emails);
+        $this->assertSame(self::FAKE_SANDBOX_ID, $emails->getSandboxId());
     }
 }
diff --git a/tests/MailtrapTestCase.php b/tests/MailtrapTestCase.php
index 6c0440f..d958c6c 100644
--- a/tests/MailtrapTestCase.php
+++ b/tests/MailtrapTestCase.php
@@ -19,6 +19,7 @@ abstract class MailtrapTestCase extends TestCase
     public const FAKE_ORGANIZATION_ID = 7777;
     public const FAKE_ACCOUNT_ACCESS_ID = 1000001;
     public const FAKE_PROJECT_ID = 2436;
+    public const FAKE_SANDBOX_ID = 4015;
     public const FAKE_INBOX_ID = 4015;
     public const FAKE_MESSAGE_ID = 457;
     public const FAKE_MESSAGE_ATTACHMENT_ID = 67;