Topic: MAIL queue on hight server load.
I run quite big installation of iRedMail (iRedAdmin Pro 1.5, iRedMail 0.7.0)
I have ~30 000 active users boxes.
Couple days ago I noticed following problem:
Sometimes queue size grows quite big (even to 1000 mails) all mails in queue are incoming mails. When I check id-s, all of them are stuck on following step:
postfix/qmgr: 61D0AF588DB: from=<email@example.com>, size=3362, nrcpt=1 (queue active)
Here are details:
cat /var/log/maillog | grep 61D0AF588DB
May 21 16:13:59 mail3 postfix/smtpd: 61D0AF588DB: client=unknown[220.127.116.11]
May 21 16:13:59 mail3 postfix/cleanup: 61D0AF588DB: message-id=<firstname.lastname@example.org>
May 21 16:14:00 mail3 postfix/qmgr: 61D0AF588DB: from=<email@example.com>, size=3362, nrcpt=1 (queue active)
May 21 16:15:57 mail3 postfix/smtp: 61D0AF588DB: to=<firstname.lastname@example.org>, relay=127.0.0.1[127.0.0.1]:10024, conn_use=150, delay=118, delays=1.2/115/0/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=06178-01-150, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 30B26F58891)
May 21 16:15:57 mail3 postfix/qmgr: 61D0AF588DB: removed
This shows all ready delivered mail but you can notice that between
May 21 16:14:00 mail3 postfix/qmgr
and next step
May 21 16:15:57 mail3 postfix/smtp
time difference is almost 2 mins (thats quite big for me)
can you advice what i need to tune up for better performance?
when queue has lots of such mails I don't experience low resources on server (cpu is ~ 60/70 % ), RAM ~50% free, not swapping, disk io is not much.
I increased amavisd $max_servers to 10 and not I don't experience errors with connection refused to 10024 but this problem with mail queue size still exists.