diff --git a/zerver/tests/test_auth_backends.py b/zerver/tests/test_auth_backends.py
index d5475fe4eb..6041b0b9a6 100644
--- a/zerver/tests/test_auth_backends.py
+++ b/zerver/tests/test_auth_backends.py
@@ -3660,6 +3660,14 @@ class TestZulipRemoteUserBackend(DesktopFlowTestingLib, ZulipTestCase):
             self.assertEqual(result.status_code, 302)
             self.assert_logged_in_user_id(user_profile.id)
 
+    def test_login_case_insensitive(self) -> None:
+        user_profile = self.example_user('hamlet')
+        email_upper = user_profile.delivery_email.upper()
+        with self.settings(AUTHENTICATION_BACKENDS=('zproject.backends.ZulipRemoteUserBackend',)):
+            result = self.client_get('/accounts/login/sso/', REMOTE_USER=email_upper)
+            self.assertEqual(result.status_code, 302)
+            self.assert_logged_in_user_id(user_profile.id)
+
     def test_login_failure(self) -> None:
         email = self.example_email("hamlet")
         result = self.client_get('/accounts/login/sso/', REMOTE_USER=email)
diff --git a/zproject/backends.py b/zproject/backends.py
index a95b347e79..cad8d397a0 100644
--- a/zproject/backends.py
+++ b/zproject/backends.py
@@ -985,7 +985,7 @@ class ExternalAuthResult:
         if self.user_profile is not None:
             # Ensure data inconsistent with the user_profile wasn't passed in inside the data_dict argument.
             assert 'full_name' not in data_dict or data_dict['full_name'] == self.user_profile.full_name
-            assert 'email' not in data_dict or data_dict['email'] == self.user_profile.delivery_email
+            assert 'email' not in data_dict or data_dict['email'].lower() == self.user_profile.delivery_email.lower()
             # Update these data_dict fields to ensure consistency with self.user_profile. This is mostly
             # defensive code, but is useful in these scenarios:
             # 1. user_profile argument was passed in, and no full_name or email_data in the data_dict arg.