The LMTP runner on my Mailman 3 install (3.1.0b4) has started silently
crashing. The parent process and all of the other runners stay up. Nothing
interesting seems to be written to the logs. I've been finding out about it
when exim4 (running on the same server) starts sending out "retry timeout
exceeded" bounce emails to list participants:
From: Mail Delivery System [mailto:Mailer-Daemon@lists.mysite.org]
> Sent: Monday, July 31, 2017 12:39 PM
> To: some_participant(a)mysite.org
> Subject: Mail delivery failed: returning message to sender
> This message was created automatically by mail delivery software.
> A message that you sent could not be delivered to one or more of its
> recipients. This is a permanent error. The following address(es) failed:
> retry timeout exceeded
> Action: failed
> Final-Recipient: rfc822;listname(a)lists.mysite.org
> Status: 5.0.0
After hearing about the bounces from participants, I then SSH to the lists
server and attempt to `telnet localhost 8024` but get no response. The LMTP
runner is not listed in `ps -ef`. After restarting all of mailman (`mailman
stop; mailman start`) I get the `220` response from LMTP on port 8024. I
see the LMTP runner in `ps -ef`.
Does anyone have any ideas on how I could start debugging this?