As a hobby, I ran a mail server (Xmail) on on old machine, just for myself and a few friends. It was very old, and the mail server was getting slower and slower, and then the greylister broke. So I got a newer old machine and set it up with Postfix on Ubuntu. Tested it on the internal network.
Everything works well. Easy install, easy set up. Tell the NAT firewall to send external smtp to it, and plonk! Every transfer times-out after connect. I check everything :-) But outgoing mail works fine. I spend three weeks trying different set ups. No luck. (I am beginning to hate Postfix, by this time). In the end I found it, the default gateway was pointing at the machine I'd taken the old mail server off. All responses to smtp connects were being routed through a blocked firewall. The moral of this story: It's almost always your fault. R. P.S. New to Postfix, but I already like it. Thanks Wietse.
