Hi guys, been struggling with this all night and think I’ve tried everything but must be missing something…
Otherwise, everything works great and I can send/received emails just fine. But one account I have just migrated over receives some (system) emails via Mailgun, which are bouncing with the following error:-
5.1.0 <firstname.lastname@example.org>: Sender address rejected: User unknown in virtual mailbox table
The ‘To’, ‘From’ and ‘Sender’ headers are
email@example.com), but the ‘Return-path’ header is something along the lines of
firstname.lastname@example.org. Is that what’s causing the issue?
Another header is:
Received: from so254-52.mailgun.net (so254-52.mailgun.net [126.96.36.199])
I’ve tried disabling ‘Sender check’ on the mailboxes, but that doesn’t seem to help.
Any ideas? Much appreciated.