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

thorsten aq5 at fatbeehive.com
Fri Sep 22 15:04:34 UTC 2006

David Hrbáč wrote:
> Well, I do not understand it now.
> domain.tld has:
> mx 20 some_server2
> mx 10 some_server1

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


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.


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