[ Thanks to Falko
Timme for this link. ]
“For two small businesses I set up a debian lenny
installation on their “home” dsl connection. The problem is that
they have dynamic ip addresses and most mailservers will not accept
incoming mail from a server on a dynamic ip address. The solution
is rather simple.“Set up postfix in a way that it will relay the outgoing email
through the actual ISP. In this short howto I’ll show you how to do
that.”