Dear Dovecot community,
we changed sieve_redirect_envelope_from to orig_recipient recently
to fix sieve redirects in case the forwarded mail comes from a
DMARC-enabled domain.
While this works well, it creates a new problem: if the receiving mail
server (the one in charge of the redirect destination) reacts with a
bounce mail, the bounce now will go to orig_recipient - the mail
address that has the redirect in place, which means no less than
creating a mail bomb (endless mail loop).
See the following example:
- alice@sender.org sends mail to jane@our-domain.org
- jane@our-domain.org has a sieve redirect to jane@redirect-target.org
- jane@redirect-target.org replies with a bounce because their mailbox is full.
- The bounce mail gets sent to jane@our-domain.org.
- The loop starts again at step 2.
Is it possible to configure dovecot/pigeonhole to *not* forward the bounce mails from step 4 again?
Probably it would work to add manual extra checks to the sieve redirect rules, but that would need to be followed by any user who configures a redirect. So I'm more looking for a server-wide configuration change that fixes this problem.
Looking forward to hear about your thoughts on the problem.
Kind regards doobry