Our MTA mail queue regularly builds up, with hundreds of mails in the queue. I've looked up several SKs, and have been working with TAC to help resolve this, without much progress, so i'm reaching out to the community for advice.
The error we see on all of the mails when this happens is:
(lost connection with 127.0.0.1[127.0.0.1] while receiving the initial server greeting).
running "/opt/postfix/usr/sbin/postqueue -c /opt/postfix/etc/postfix/ -f " doesnt force the mails through the queue.
The only real changes recently that could affect this blade have been moving to Jumbo take 154, which happened a little while before the issue began, and several weeks before this issue appeared we changed the main.cf to use the correct mail header.
The mails eventually release once the maximum delay time has been hit.
CPU usage is generally sitting at 50% idle, but does have occasional spikes to <10% idle.