Postfix oddity - not acknowledging mails
My mail server is in my office, on the end of an ADSL connection. If I talk to the SMTPd from my LAN, all goes as expected. If I do it remotely (like from my Linode, which is also the backup MX), I either never get the 250 after sending the
From my Linode, if I use Lynx to go to the same server, where I run my intranet/extranet, I get no problems talking HTTP.
Anyone got any idea what might be amiss? The multiple messages are annoying, but when people start getting notifications that their messages couldn't be delivered after I have received them many times - well, that's when it will get worse.
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It is behind a firewall which does NAT and passes on SMTP, etc., packets by port-forwarding. The firewall is part of the D-Link ADSL router. Never given problems before.
DNS problems? I don't know. Sometime late yesterday the problem resolved - but not as a result of all the fiddling that I had been doing, it just happened. When I saw that I wasn't getting repeating mails anymore, I SSH'd into both of my Linodes, tried the telnet test again and got the acknowledgments back without any problems.
Mail was going out OK, so it must have been resolving then, and I was able to use other services normally. However, I cannot eliminate some transient DNS issue.
I almost wish that it had stayed broken as the sudden disappearance of the problem makes it all the more puzzling.