diff --git a/src/gaia/connectors/formatting.py b/src/gaia/connectors/formatting.py
index fc58363f6..edb7dd13f 100644
--- a/src/gaia/connectors/formatting.py
+++ b/src/gaia/connectors/formatting.py
@@ -30,14 +30,20 @@
 )
 
 # Per-agent override messages for ``AGENT_NOT_GRANTED``. Keyed by
-# ``namespaced_agent_id`` (matches the ``agent_id`` field on
-# ``AuthRequiredError``). Used to surface a more specific upgrade-path
-# message when an existing user's grant predates a scope addition (e.g. a
-# user who connected Google before #962 has no ``gmail.modify`` grant; the
-# first organize/trash/send tool call raises ``AGENT_NOT_GRANTED`` and we
-# want them to see exactly how to fix it).
-_AGENT_GRANT_MIGRATION_MESSAGES: Dict[str, str] = {
-    "installed:email": (
+# ``(namespaced_agent_id, provider)`` (matching the ``agent_id`` and
+# ``provider`` fields on ``AuthRequiredError``). Used to surface a more
+# specific upgrade-path message when an existing user's grant predates a
+# scope addition (e.g. a user who connected Google before #962 has no
+# ``gmail.modify`` grant; the first organize/trash/send tool call raises
+# ``AGENT_NOT_GRANTED`` and we want them to see exactly how to fix it).
+#
+# The provider is part of the key so a per-provider override never shadows
+# another provider's failure: the email agent now serves both Google and
+# Microsoft mailboxes, and a Microsoft grant gap must NOT show Google
+# "Reconnect" instructions. Providers without a tailored entry fall through
+# to the generic provider-aware branch below.
+_AGENT_GRANT_MIGRATION_MESSAGES: Dict[tuple[str, str], str] = {
+    ("installed:email", "google"): (
         "Email agent needs additional Google permissions "
         "(gmail.modify, gmail.send, calendar.events). "
         "Open Settings → Connectors → Google → Reconnect to grant the "
@@ -53,13 +59,17 @@ def format_connector_error(e: BaseException) -> str:
     Settings → Connections (``AGENT_NOT_GRANTED`` and ``NOT_CONNECTED``)
     are surfaced explicitly so agents can tell the user where to go.
 
-    For agents registered in ``_AGENT_GRANT_MIGRATION_MESSAGES``, the
-    ``AGENT_NOT_GRANTED`` reason returns the agent-specific upgrade
-    message instead of the generic one.
+    For ``(agent_id, provider)`` pairs registered in
+    ``_AGENT_GRANT_MIGRATION_MESSAGES``, the ``AGENT_NOT_GRANTED`` reason
+    returns the agent-specific upgrade message instead of the generic one;
+    any provider without a tailored entry falls through to the generic
+    provider-aware message.
     """
     if isinstance(e, AuthRequiredError):
         if e.reason is AuthRequiredError.Reason.AGENT_NOT_GRANTED:
-            override = _AGENT_GRANT_MIGRATION_MESSAGES.get(e.agent_id or "")
+            override = _AGENT_GRANT_MIGRATION_MESSAGES.get(
+                (e.agent_id or "", e.provider or "")
+            )
             if override:
                 return override
             scopes = ", ".join(e.missing_scopes) or "(none reported)"
diff --git a/tests/unit/connectors/test_formatting.py b/tests/unit/connectors/test_formatting.py
index 13bd14601..8be952c66 100644
--- a/tests/unit/connectors/test_formatting.py
+++ b/tests/unit/connectors/test_formatting.py
@@ -88,6 +88,30 @@ def test_format_connector_error_email_agent_grant_migration():
     assert "Reconnect" in msg
 
 
+def test_format_connector_error_email_agent_microsoft_falls_through():
+    """
+    A Microsoft grant gap for ``installed:email`` must NOT show the Google
+    "Reconnect" migration text (issue #1751). The override is keyed by
+    ``(agent_id, provider)``, so a Microsoft failure falls through to the
+    generic provider-aware branch — naming Microsoft and the missing Graph
+    scopes, not Google.
+    """
+    err = AuthRequiredError(
+        AuthRequiredError.Reason.AGENT_NOT_GRANTED,
+        provider="microsoft",
+        agent_id="installed:email",
+        missing_scopes=["Mail.ReadWrite", "Mail.Send"],
+    )
+    msg = format_connector_error(err)
+    assert "AGENT_NOT_GRANTED" in msg
+    assert "microsoft" in msg
+    assert "Mail.ReadWrite" in msg
+    assert "Mail.Send" in msg
+    # The Google migration string must not leak onto a Microsoft failure.
+    assert "Google" not in msg
+    assert "gmail.modify" not in msg
+
+
 def test_format_connector_error_unknown_agent_falls_back_to_generic():
     """An agent without a registered override gets the generic message."""
     err = AuthRequiredError(