MTA / DNS strangeness
All of a sudden, Zimbra Network Edition 4.0.1 is experiencing problems sending mail.
What seems to be happening, is instead of postfix looking up the MX record for outgoing mail, it's only looking up the A record and attempting to send to that. Here's an example:
Sep 25 14:46:18 hickory postfix/qmgr: 86E2D520004: to=<"someone"@msn.com>, relay=none, delay=5, status=deferred (delivery temporarily suspended: connect to msn.com[18.104.22.168]: Connection timed out)
If you do a ns lookup for the A record of msn.com, you'll see that it's the 22.214.171.124 as above, but the MX records for msn.com are completely different IPs. This just started all of a sudden, and I can't figure out why.
After searching the forums some more, I found this post http://www.zimbra.com/forums/showthr...light=A+record
which looks like exactly the problem I was having. I even had disabled DNS lookups last week like that poster did. However, after re-enabling DNS lookups, the problem was still happening. I restarted postfix, and then Zimbra altogether, and it was still a problem. I'm thinking possibly that setting didn't take, somehow.
With over 300 messages in the queue unable to be delivered, I finally quickly set up another machine to be an SMTP relay and configured Zimbra to send through that server. A temporary workaround, but if anyone has any more insight into this issue, let me know! :)
You can use your ISP's SMTP server.
zmprov gcf zimbraMtaDnsLookupsEnalbed
zmprov gs hickory.domain.com | grep DnsLookups