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.
