diff --git a/.claude/board/STATUS_BOARD.md b/.claude/board/STATUS_BOARD.md
index fae8c6a75..bf5d852c7 100644
--- a/.claude/board/STATUS_BOARD.md
+++ b/.claude/board/STATUS_BOARD.md
@@ -33,7 +33,8 @@ Decision 1(c): observed claims, provisioning conflicts and delivery are three qu
 
 | D-id | Deliverable | Status | Gate |
 |---|---|---|---|
-| **D-DSV-1** | `validate::provisioning_conflicts`: every present object's claims, separate from `address_owner` / `address_recipient` / `validate` | In PR | `tests/provisioning.rs`: delivery unchanged, conflict reported, silence half; two disable runs red |
+| **D-DSV-1** | `validate::provisioning_conflicts`: every present object's claims, separate from `address_owner` / `address_recipient` / `validate` | Shipped (#1477, #1480) | `tests/provisioning.rs`: delivery unchanged, conflict reported, silence half; two disable runs red |
+| **D-DSV-2** | A mail-enabled group's secondary SMTP proxies are in the Exchange address space (a group without a primary SMTP address claims them only in the provisioning plane): mail to them reaches the group (`address_owner` / `address_recipient`), and an object sharing one is an `AddressConflict` | In PR | `tests/provisioning.rs`: `mail_to_a_groups_secondary_proxy_reaches_the_group` red before; `a_groups_secondary_proxy_claims_its_address` re-pinned from owner to conflict; `a_non_mail_enabled_groups_proxy_is_only_a_provisioning_claim` red before (Codex P1) |
 
 ## D-DSP — dir-sim history that survives a restart (2026-10-11)
 
diff --git a/crates/lance-graph-dir-sim/src/validate.rs b/crates/lance-graph-dir-sim/src/validate.rs
index 0db3ac70e..3b92b4293 100644
--- a/crates/lance-graph-dir-sim/src/validate.rs
+++ b/crates/lance-graph-dir-sim/src/validate.rs
@@ -459,7 +459,8 @@ pub fn address_rules(v: &View<'_>) -> Vec<Violation> {
 /// The single directory object that holds `key` in the one address space
 /// [`address_rules`] checks, read from the same rows: UPN, primary and
 /// secondary SMTP and the routing address of address owners; the primary
-/// SMTP address of every live group. `mail` holds nothing.
+/// and secondary SMTP addresses of every mail-enabled group (one with a
+/// primary SMTP address). `mail` holds nothing.
 ///
 /// - `Ok(None)`: no live directory object holds the key.
 /// - `Ok(Some(owner))`: exactly one does, under one or more roles (a user
@@ -541,17 +542,24 @@ pub fn address_recipient_in(
 fn address_rows(v: &View<'_>, out: &mut Vec<Violation>) -> Vec<(u32, Guid128, AddressRole)> {
     // The UPN is held by an enabled account or a live recipient; the mail
     // addresses are provisioned by the recipient type alone.
-    rows_over(v, &v.owner_users(), &v.mail_owner_users(), out)
+    rows_over(v, &v.owner_users(), &v.mail_owner_users(), false, out)
 }
 
 /// The `(key, holder, role)` rows of the users in `owners` (their UPN)
 /// and `mail_owners` (their primary and secondary SMTP and routing
-/// address), and of every live group (its primary SMTP), sorted and
-/// deduplicated. Routing violations of `mail_owners` go to `out`.
+/// address), and of every live group (its primary and secondary SMTP),
+/// sorted and deduplicated. Routing violations of `mail_owners` go to `out`.
+///
+/// `every_group_proxy` decides which groups' secondary proxies count: in
+/// Exchange (`false`) only a mail-enabled group's, the one that has a
+/// primary SMTP address, since a group that is not mail-enabled holds and
+/// receives at nothing; in the provisioning plane (`true`) every present
+/// group's, since Entra keeps proxy addresses unique whatever the object.
 fn rows_over(
     v: &View<'_>,
     owners: &[u64],
     mail_owners: &[u64],
+    every_group_proxy: bool,
     out: &mut Vec<Violation>,
 ) -> Vec<(u32, Guid128, AddressRole)> {
     let p = &v.snap.users;
@@ -615,19 +623,30 @@ fn rows_over(
             out.push(Violation::RoutingMismatch { node: g });
         }
     }
-    // A mail-enabled group's primary SMTP address is in the same space: a
-    // group is a recipient too (a distribution list), and Exchange refuses
-    // an address another object holds, whatever kind that object is.
+    // A mail-enabled group's SMTP addresses are in the same space: a group
+    // is a recipient too (a distribution list), Exchange delivers mail sent
+    // to any of its SMTP proxies, and it refuses an address another object
+    // holds, whatever kind that object is. A group created in a version
+    // carries no secondary proxies (a `Change` sets none), so only observed
+    // groups have proxy rows.
+    let gp = &v.snap.group_proxies;
     for i in 0..v.groups_len() {
         let Some(g) = v.guid_in(NodeKind::Group, i) else {
             continue;
         };
-        if let Some((_, k)) = v
+        let primary = v
             .attr_ids((NodeKind::Group, i), Attribute::PrimarySmtp)
-            .filter(|&(_, k)| k != NONE)
-        {
+            .filter(|&(_, k)| k != NONE);
+        if let Some((_, k)) = primary {
             rows.push((k, g, AddressRole::PrimarySmtp));
         }
+        if (every_group_proxy || primary.is_some()) && i < v.snap.groups.len() {
+            for r in gp.owner_rows(i as u32) {
+                if gp.meta[r] == meta::SMTP_SECONDARY {
+                    rows.push((gp.key[r], g, AddressRole::SecondarySmtp));
+                }
+            }
+        }
     }
     rows.sort_unstable();
     rows.dedup();
@@ -679,22 +698,7 @@ pub struct ProvisioningConflict {
 /// real tenant and are not in this plane.
 pub fn provisioning_conflicts(v: &View<'_>) -> Vec<ProvisioningConflict> {
     let present = v.existing(NodeKind::User);
-    let mut rows = rows_over(v, &present, &present, &mut Vec::new());
-    // A group's secondary SMTP proxies claim too. A group created in a
-    // version carries none (a `Change` sets no proxy).
-    let gp = &v.snap.group_proxies;
-    for i in 0..v.snap.groups.len() {
-        let Some(g) = v.guid_in(NodeKind::Group, i) else {
-            continue;
-        };
-        for r in gp.owner_rows(i as u32) {
-            if gp.meta[r] == meta::SMTP_SECONDARY {
-                rows.push((gp.key[r], g, AddressRole::SecondarySmtp));
-            }
-        }
-    }
-    rows.sort_unstable();
-    rows.dedup();
+    let rows = rows_over(v, &present, &present, true, &mut Vec::new());
     rows.chunk_by(|a, b| a.0 == b.0)
         .filter(|run| run.iter().any(|r| r.1 != run[0].1))
         .map(|run| ProvisioningConflict {
diff --git a/crates/lance-graph-dir-sim/tests/provisioning.rs b/crates/lance-graph-dir-sim/tests/provisioning.rs
index a54978d98..9047dfc7b 100644
--- a/crates/lance-graph-dir-sim/tests/provisioning.rs
+++ b/crates/lance-graph-dir-sim/tests/provisioning.rs
@@ -130,8 +130,11 @@ fn distinct_claims_and_one_object_under_two_roles_are_not_conflicts() {
 }
 
 // A group's secondary SMTP proxy claims like any other address: another
-// object carrying it is a provisioning conflict. Delivery still reads a
-// group by its primary address only, so the user keeps the address there.
+// object carrying it is a provisioning conflict. It is also held in
+// Exchange (mail to it reaches the group), so a user carrying the same
+// address shares the key and the address names no single recipient.
+// (Before #45 delivery read a group by its primary address only, and this
+// test pinned the user as the owner.)
 #[test]
 fn a_groups_secondary_proxy_claims_its_address() {
     let mut grp = group("team@x.test");
@@ -148,7 +151,80 @@ fn a_groups_secondary_proxy_claims_its_address() {
         st.key_of(id).unwrap()
     };
     let view = st.view(v).unwrap();
+    let holders = vec![
+        (g(0xA1), AddressRole::PrimarySmtp),
+        (g(0xB0), AddressRole::SecondarySmtp),
+    ];
+    assert_eq!(
+        address_owner(&view, key),
+        Err(Violation::AddressConflict {
+            key,
+            holders: holders.clone()
+        })
+    );
+    assert_eq!(
+        address_recipient(&view, key),
+        Err(Violation::AddressConflict {
+            key,
+            holders: holders.clone()
+        })
+    );
+    assert_eq!(
+        provisioning_conflicts(&view),
+        vec![ProvisioningConflict {
+            key,
+            claims: vec![
+                (g(0xA1), AddressRole::PrimarySmtp),
+                (g(0xB0), AddressRole::SecondarySmtp),
+            ],
+        }]
+    );
+}
+
+// Exchange delivers mail sent to any of a distribution group's SMTP
+// proxies, not only its primary address: the secondary proxy is held by
+// the group and delivers to it.
+#[test]
+fn mail_to_a_groups_secondary_proxy_reaches_the_group() {
+    let mut grp = group("team@x.test");
+    grp.proxies = vec!["smtp:sales@x.test".into()];
+    let (mut st, v) = store(vec![(g(0xB0), grp)]);
+    let key = {
+        let id = st.intern("sales@x.test");
+        st.key_of(id).unwrap()
+    };
+    let view = st.view(v).unwrap();
+    assert_eq!(address_owner(&view, key), Ok(Some(g(0xB0))));
+    assert_eq!(address_recipient(&view, key), Ok(Some(g(0xB0))));
+    assert_eq!(st.validate(v).unwrap(), vec![]);
+}
+
+// A group with no primary SMTP address is not mail-enabled: its leftover
+// secondary proxy is not held in Exchange and delivers nowhere, so a user
+// carrying the same address keeps it. The leftover still claims the key in
+// the provisioning plane.
+#[test]
+fn a_non_mail_enabled_groups_proxy_is_only_a_provisioning_claim() {
+    let mut grp = ObservedNode::group();
+    grp.proxies = vec!["smtp:sales@x.test".into()];
+    let (mut st, v) = store(vec![
+        (g(0xB0), grp),
+        (
+            g(0xA1),
+            ObservedNode::user("alice.upn@x.test", "sales@x.test"),
+        ),
+    ]);
+    let key = {
+        let id = st.intern("sales@x.test");
+        st.key_of(id).unwrap()
+    };
+    let view = st.view(v).unwrap();
+    assert!(
+        !view.is_mail_recipient(&g(0xB0)),
+        "fixture: not mail-enabled"
+    );
     assert_eq!(address_owner(&view, key), Ok(Some(g(0xA1))));
+    assert_eq!(address_recipient(&view, key), Ok(Some(g(0xA1))));
     assert_eq!(
         provisioning_conflicts(&view),
         vec![ProvisioningConflict {