Large mail queues

Joan Bryan joan.bryan at KCL.AC.UK
Fri Feb 1 14:48:15 GMT 2002

On Fri, 1 Feb 2002 14:07:56 +0000 Julian Field <jkf at ECS.SOTON.AC.UK>

> Have you tried switching off spam detection, or using "Delivery in
> Background = yes".
> The sleep(30) is only used when there is very little/no incoming mail anyway.

We did switch off spam detection (we weren't supposed to be running
with this option but did for a while. Also spam assassin was not
used at all). I suppose this might have caused the queues to build up

We also tried "Delivery in Background = yes" for a short while,
although could not see an effect with this. I'll try this again.

> Perhaps other people with large throughput might like to comment?
> (I don't like the "-q1m" solution at all, it was suggested by someone else).
> At 11:55 01/02/2002, you wrote:
> >However we did have a few problems initially with very large mail queues
> >building up when we went live. (From our usual number of about 600 to 15500)
> >
> >We did several things to improve matters and thought these might be of
> >interest to others in similar situations.
> >
> >1. Changed the sleep(30) to sleep(2) (the delay time between mailscanner
> >selecting the next batch to process) in mailscanner. We were finding the
> >incoming mail building up faster than mailscanner could cope because of this
> >delay. It would be nice if this were a configurable parameter.
> >
> >2. Once the queues had built up to this size things deteriorated further
> >because of problems unix has with large directory sizes, and this slowed
> >down mailscanner's ability to process the queue so we recreated the queues
> >from scratch and started afresh.
> >
> >3. Sendmail change - this was not really anything to do with mailscanner,
> >but it helped the faster delivery of local mail. We started an additional
> >sendmail process for the output queue with parameter of -qRkcl (where kcl is
> >our local domain) to process local mail.
> >
> >4.  The -q1m parameter on sendmail was used (as suggested in the FAQ).
> --
> Julian Field                Teaching Systems Manager
> jkf at         Dept. of Electronics & Computer Science
> Tel. 023 8059 2817          University of Southampton
>                              Southampton SO17 1BJ

Joan Bryan
joan.bryan at

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