----- Message from Viktor Dukhovni <postfix-us...@dukhovni.org> ---------
Date: Wed, 29 Nov 2017 07:08:13 +0000
From: Viktor Dukhovni <postfix-us...@dukhovni.org>
Reply-To: postfix-users@postfix.org
Subject: Re: Slow delivery of mails reg.
To: postfix-users@postfix.org
On Wed, Nov 29, 2017 at 12:04:14PM +0530, an...@isac.gov.in wrote:
To understand why delivery was slow you need to analyze your logs
and examine the "delays=" log entries to see whether the delays
in connecting to the relay host or waiting for deliveries to
complete.
-- Viktor.
The log entries with delays is as below.
relay=x.x.x.x[x.x.x.x]:25, conn_use=3, delay=32027, delays=31986/31/0/10
Well, the main issue here is the consistent 10s delay to complete
a delivery after 0s connection latency. I would guess that's some
sort of timeout on the relay end resolving the IP address of the
connecting client. With 10s to complete each delivery, your
throughput is not surprisingly quite low.
relay=x.x.x.x[x.x.x.x]:25,conn_use=5, delay=27740, delays=27690/40/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=6, delay=13069, delays=13010/49/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=7, delay=21476, delays=21406/60/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=2, delay=33553, delays=33474/69/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=12, delay=14591, delays=14493/88/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=4, delay=25953, delays=25807/136/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=6, delay=27339, delays=25970/1359/0/10,
relay=x.x.x.x[x.x.x.x]:25,conn_use=16, delay=7608, delays=4510/3088/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=19, delay=7457, delays=2593/4854/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=20, delay=38734, delays=33864/4860/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=7, delay=11656, delays=5728/5918/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=19, delay=40339, delays=31320/9009/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=13, delay=10820, delays=441/10369/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=10, delay=39517, delays=29103/10404/0/10
relay=x.x.x.x[x.x.x.x]:25,conn_use=28, delay=43790, delays=33444/10336/0/10
the above log entries are at different times on the same day.
Please share your analysis for further improving our setup.
Fix the downstream delivery latency. The relay is either having
trouble with DNS resolution or is actively misconfigured to impose
an artificial delay on client connections, perhaps some sort of
anti-spam measure that could make some sense on a host getting
mail directly from the Internet, but is a bad idea for internal
relays.
-- Viktor.
Thank you so much for the debugging. We have a PIX sitting between
client and relay host and what I could see as part of default
configuration that, smtp_pix_workaround_delay_time is 10s. Could PIX
be a factor in delivery latency?
I don't see 10s delay during normal operations, but I do see "enabling
PIX workarounds: disable_esmtp delay_dotcrlf for" lines in the logs
for the relay in question.
Do you think, PIX could be the reason?
Regards,
ANANT
----- End message from Viktor Dukhovni <postfix-us...@dukhovni.org> -----
Anant S Athavale
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