return 5** if CannotCreateContactForReverseAlias

app/email/status.py

@@ -59,4 +59,5 @@ E522 = (
     "at a rate that prevents additional messages from being delivered."
 )
 E523 = "550 SL E523 Unknown error"
+E524 = "550 SL E524 Wrong use of reverse-alias"
 # endregion

app/models.py

@@ -1574,7 +1574,7 @@ class Contact(Base, ModelMixin):
         # make sure contact.website_email isn't a reverse alias
         orig_contact = Contact.get_by(reply_email=website_email)
         if orig_contact:
-            raise CannotCreateContactForReverseAlias
+            raise CannotCreateContactForReverseAlias(str(orig_contact))
 
         Session.add(new_contact)
 

email_handler.py

@@ -133,6 +133,7 @@ from app.errors import (
     VERPForward,
     VERPReply,
     MailSentFromReverseAlias,
+    CannotCreateContactForReverseAlias,
 )
 from app.log import LOG, set_message_id
 from app.models import (
@@ -2335,6 +2336,21 @@ class MailHandler:
         try:
             ret = self._handle(envelope, msg)
             return ret
+
+        # happen if reverse-alias is used during the forward phase
+        # as in this case, a new reverse-alias needs to be created for this reverse-alias -> chaos
+        except CannotCreateContactForReverseAlias as e:
+            LOG.w(
+                "Probably due to reverse-alias used in the forward phase, "
+                "error:%s mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s",
+                e,
+                envelope.mail_from,
+                envelope.rcpt_tos,
+                msg[headers.FROM],
+                msg[headers.TO],
+            )
+            Session.rollback()
+            return status.E524
         except Exception as e:
             LOG.e(
                 "email handling fail with error:%s mail_from:%s, rcpt_tos:%s, header_from:%s, header_to:%s, saved to %s",