[Mailman-Users] Huge slowdown reflected in smtp logs

Mark Sapiro msapiro at value.net
Mon Jul 24 20:24:43 CEST 2006

Craig Pettersen wrote:

>  A couple of months ago we added a 35,000 member list to our new mailman
>installation.   Checking the mailman smtp logs, we were very please with the
>performance - the whole list went out in 250 seconds.  Individual messages
>were logging in at a fraction of a second.  Mailings to this newsletter list
>go out about every 2-3 weeks.  The first three mailings went out just fine -
>one in as little as 43 seconds to all 35000 members.  But suddenly the time
>shot up to over 4000 seconds on the fourth mailing, and individual messages
>are going out at between 3 and 120 seconds.  Subsequent mailings have had
>similar numbers and haven't coincided with any particularly busy times for
>the server, nor has any configuration of the server been changed.  We use
>qmail, by the way.
>   I'm not sure how to account for this huge slowdown.

This is between Mailman and your outgoing MTA. See

If you haven't changed things like SMTP_MAX_RCPTS,
mm_cfg.py, it almost has to be because of some change outside Mailman.

>I suspect it may
>have something to do with the bounce system, because it was the fourth
>mailing that we first saw a reduction (about 500) in the mailing due to
>bounce-disabled subscribers.  Currently there are about 11000
>bounce-disabled subscribers which is not particularly a concern since the
>list had never been purged before.

I don't think it has anything to do with bounces in any way. Members
who are 'bounce disabled' have absolutely no effect on smtp delivery
to the list other than the fact they aren't being delivered to. If
anything, having some members who are disabled rather that not, would
speed up the smtp delivery.

>I would just like to know if anyone out
>there might have a clue as to the cause of the slowdown and if there might
>be anything we can do to speed things up.

See the FAQ referred to above and the others it points to. I think
something must have changed in the MTA or the underlying

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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