Work has two external valid IPs with seperate mail servers listening. Today I needed to configure one of the mail servers to forward mail to the other (main) server while rejecting anything not for our domain.
The main entries to go in
# The domains that the server will accept mail for relay_domains = $myhostname, hash:/etc/postfix/relay_domains # The transport mapping for each domain transport_maps = hash:/etc/postfix/transport
A sample entry for
relay_domains is as follows, detailing the domains that we want to act as a relay for:
example1.com OK example2.com OK
and a sample entry of the
example1.com smtp:server.domain1.com example2.com smtp:server.domain2.com
As usual, the two files need to be converted to their db counterparts:
$ postmap relay_domains $ postmap transport
Restart postfix for the changes to take place.
Credit where credit is due: http://www.binarytides.com/postfix-mail-forwarding-debian/