[CentOS] postfix problem since update: mail loops back to myself

David Hrbáč hrbac.conf at seznam.cz
Fri Sep 22 15:13:08 UTC 2006

thorsten napsal(a):
> The problem occurs on domain.tld == some_server1, which is a mail server.
> domain.tld does backups for some_server2.tld and vice versa.
> so, domain.tld has:
> mx 20 some_server2.tld (so, they do backup in case our server is down)
> mx 10 domain.tld (this server. should deliver mails for domain.tld)
> if some_server2.tld (which for we are doing mx backup as well) is down,
> our system keeps mails but does not deliver them.
> BUT: (and that's the problem)
> if one of us here on domain.tld wants to send an email to
> some_server2.tld, then this problem with 'loops back to me' occurs
> (since centos update).
> so IMO, it is correct having
> postmap -q some_server2.tld mysql:/etc/postfix/sql/transport
> returning smtp:some_server2.tld
> and
> postmap -q domain.tld mysql:/etc/postfix/sql/transport
> returning maildrop:
> so, if mails for some_server2.tld are arriving at domain.tld, it tries
> to forward them via smtp to some_server2.tld which should be done via:
> smtp      inet  n       -       n       -       25      smtpd
> (from master.cf), AFAIK
> and EVEN, if I REMOVE the mysql entry for smtp:some_server2.tld, so it
> should appear to postfix like every other domain in the world, postfix
> finds a loop back to itself.
> And that's, what I don't understand.
> This configuration was already working and productive.
> thorsten.

OK, so let's sum it up.

Let's have domain1.tld and domain2.tld.

domain1.tld has:
20 server.domain2.tld
10 server.domain1.tld

domain2.tld has:
20 server.domain1.tld
10 server.domain2.tld

on server.domain1.tld we need to have:
domain1.tld within virtual domains or local domain
domain2.tld within transport

on server.domain2.tld we need to have:
domain2.tld within virtual domains or local domain
domain1.tld within transport


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