On 7 Sep 2011, at 09:39, Nigel Metheringham wrote:

> 
> On 7 Sep 2011, at 02:09, Always Learning wrote:
> 
>> Mailing list emails sent to me show a 30 minute delay at Tahini.
> 
> Finding it hard to care here.  Mailing lists are not supposed to be
> a real time medium.
> 

They're not, but users are generally used to fairly short lags, and short lags 
do make conversations flow better. For announcement lists, a 40 minute delay 
means nothing, but for a discussion list, regular 40 minute delays would be 
unfortunate.

At Sussex, *all* our mailing lists are VERPd, and by Mailman not Exim. We did 
see problems where occasional use of a very large list would delay messages on 
all lists, by flooding the outgoing queue runner.

We mitigated delays by using a higher number of Mailman outgoing queue runners. 
We have this in Mailman/mm_cfg.py:

QRUNNERS = [
    ('ArchRunner',     4), # messages for the archiver
    ('BounceRunner',   4), # for processing the qfile/bounces directory
    ('CommandRunner',  4), # commands and bounces from the outside world
    ('IncomingRunner', 4), # posts from the outside world
    ('NewsRunner',     4), # outgoing messages to the nntpd
    ('OutgoingRunner', 32), # outgoing messages to the smtpd
    ('VirginRunner',   4), # internally crafted (virgin birth) messages
    ('RetryRunner',    4), # retry temporarily failed deliveries
    ]

The 32 outgoing queue runners mean that slow recipient hosts aren't such a 
problem.

You can also set VERP_DELIVERY_INTERVAL to something other than 1, to reduce 
the VERP overhead.

-- 
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148


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