diff --git a/src/common/helper.ts b/src/common/helper.ts
index 7254e65..f7e75b7 100644
--- a/src/common/helper.ts
+++ b/src/common/helper.ts
@@ -1973,7 +1973,10 @@ function buildPhaseChangeEmailData({
 }
 
 /**
- * Send phase change notification
+ * Send phase change notification.
+ * Publishes one email event per recipient so member email addresses are never
+ * shared in a single To field. A failed publish is logged and does not stop the
+ * remaining recipients from being notified.
  * @param {String} type the notification type
  * @param {Array} recipients the array of recipients emails
  * @param {Object} data the data
@@ -2000,14 +2003,20 @@ async function sendPhaseChangeNotification(type, recipients, data) {
       return;
     }
 
-    await postBusEvent("external.action.email", {
-      from: config.EMAIL_FROM,
-      replyTo: config.EMAIL_FROM,
-      recipients: safeRecipients,
-      data: data,
-      sendgrid_template_id: settings.sendgridTemplateId,
-      version: "v3",
-    });
+    for (const recipient of safeRecipients) {
+      try {
+        await postBusEvent("external.action.email", {
+          from: config.EMAIL_FROM,
+          replyTo: config.EMAIL_FROM,
+          recipients: [recipient],
+          data: data,
+          sendgrid_template_id: settings.sendgridTemplateId,
+          version: "v3",
+        });
+      } catch (e) {
+        logger.debug(`Failed to post notification ${type} to a recipient: ${e.message}`);
+      }
+    }
   } catch (e) {
     logger.debug(`Failed to post notification ${type}: ${e.message}`);
   }
diff --git a/test/unit/phase-change-notification-helper.test.js b/test/unit/phase-change-notification-helper.test.js
new file mode 100644
index 0000000..62e2824
--- /dev/null
+++ b/test/unit/phase-change-notification-helper.test.js
@@ -0,0 +1,88 @@
+require("../../app-bootstrap");
+
+const { expect } = require("chai");
+const constants = require("../../app-constants");
+
+const helperPath = require.resolve("../../src/common/helper");
+const busApiPath = require.resolve("topcoder-bus-api-wrapper");
+
+describe("phase change notification helper", () => {
+  const settings = constants.PhaseChangeNotificationSettings.PHASE_CHANGE;
+  const originalTemplateId = settings.sendgridTemplateId;
+  const originalHelperModule = require.cache[helperPath];
+  const originalBusApiModule = require.cache[busApiPath];
+  let postedEvents;
+  let failingRecipients;
+  let helper;
+
+  beforeEach(() => {
+    postedEvents = [];
+    failingRecipients = new Set();
+    settings.sendgridTemplateId = "phase-change-template";
+
+    // Load a fresh helper bound to a stub bus client so published events can be inspected.
+    require.cache[busApiPath] = {
+      id: busApiPath,
+      filename: busApiPath,
+      loaded: true,
+      exports: () => ({
+        postEvent: async (message) => {
+          if (failingRecipients.has(message.payload.recipients[0])) {
+            throw new Error("bus unavailable");
+          }
+          postedEvents.push(message);
+        },
+      }),
+    };
+    delete require.cache[helperPath];
+    helper = require(helperPath);
+  });
+
+  afterEach(() => {
+    settings.sendgridTemplateId = originalTemplateId;
+    require.cache[helperPath] = originalHelperModule;
+    if (originalBusApiModule) {
+      require.cache[busApiPath] = originalBusApiModule;
+    } else {
+      delete require.cache[busApiPath];
+    }
+  });
+
+  it("publishes a separate email event for each recipient", async () => {
+    const data = { challengeName: "Design challenge", phase_change: "Registration Closed" };
+
+    await helper.sendPhaseChangeNotification(
+      "PHASE_CHANGE",
+      ["alice@example.com", "", "bob@example.com"],
+      data,
+    );
+
+    expect(postedEvents).to.have.length(2);
+    expect(postedEvents.map((event) => event.topic)).to.deep.equal([
+      "external.action.email",
+      "external.action.email",
+    ]);
+    expect(postedEvents.map((event) => event.payload.recipients)).to.deep.equal([
+      ["alice@example.com"],
+      ["bob@example.com"],
+    ]);
+    postedEvents.forEach((event) => {
+      expect(event.payload.data).to.deep.equal(data);
+      expect(event.payload.sendgrid_template_id).to.equal("phase-change-template");
+    });
+  });
+
+  it("continues notifying remaining recipients when one publish fails", async () => {
+    failingRecipients.add("alice@example.com");
+
+    await helper.sendPhaseChangeNotification(
+      "PHASE_CHANGE",
+      ["alice@example.com", "bob@example.com"],
+      {},
+    );
+
+    expect(postedEvents.map((event) => event.payload.recipients)).to.deep.equal([
+      ["bob@example.com"],
+    ]);
+  });
+});