create a notification when an alias is disabled

email_handler.py

@@ -1403,6 +1403,15 @@ def handle_bounce_forward_phase(msg: Message, email_log: EmailLog):
         alias.enabled = False
         Session.commit()
 
+        Notification.create(
+            user_id=user.id,
+            title=f"{alias.email} has been disabled due to multiple bounces",
+            message=Notification.render(
+                "notification/alias-disable.html", alias=alias, mailbox=mailbox
+            ),
+            commit=True,
+        )
+
         send_email_with_rate_control(
             user,
             ALERT_BOUNCE_EMAIL,

templates/notification/alias-disable.html

@@ -0,0 +1,10 @@
+<div>
+  There are several emails sent to your alias <b>{{ alias.email }}</b> that have been bounced by your
+  mailbox <b>{{ mailbox.email }}</b>.
+</div>
+
+<div>
+  As security measure, we have disabled the alias <b>{{ alias.email }}</b>.
+
+</div>
+