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Subject: Re: queue overflow.
From: Wietse Venema (wietseporcupine.org)
Date: Wed Jun 07 2000 - 18:32:54 CDT

Rask Ingemann Lambertsen:
> Den 24-Maj-00 15:36:36 skrev Wietse Venema f_lgende om "Re: queue overflow.":
> >cresce t. arenas iii:
> >> Hi, there need help on this problem, what could be the cause.
> >>
> >> May 24 11:49:51 rajah2
> >> postfix/qmgr[31730]: 651475875E: to=<poksiepworld.net.ph>, relay=none,
> >> delay=4650, status=deferred (site destination queue overflow)
>
> >It just means that Postfix was saturating with mail for one
> >destination, and decided to defer the remainder, so that other mail
> >could be delivered.
>
> There are no ill effects from it, are there? If it happens often, would
> there be a significant benefit from changing the configuration so that it
> doesn't happen?

Dealing with congestion is difficult. Postfix uses a finite buffer
(active queue) to look ahead in the queue. If the entire lookahead
buffer fills up with mail for the same destination, then Postfix
can no longer spread its efforts over multiple destinations and
concurrency suffers.

One solution is to disable the feature and just allow Postfix to
be saturated with mail one site, but that would be detrimental for
deliveries to other sites.

    qmgr_site_hog_factor = 100

On the other hand, if this is a firewall mail gateway, then half
the mail is expected to be inbound, and deferring the inbound mail
may not achieve what you want. You may be able to flush the queue
faster by removing the per-transport destination concurrency
controls, but only if the internal destination can handle dozens
of connections without being swamped.

        Wietse