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Re: Bug#510415: tech-ctte: Qmail inclusion (or not) in Debian

Adeodato Simó <dato@net.com.org.es> writes:
> * Russ Allbery [Wed, 04 Feb 2009 14:02:21 -0800]:

>> It's a great workaround for small lists and not so great for large
>> lists with lots of recipients at the same destination server.

> AFAIK the Debian lists use VERP, and they are, erm, not that small.
> Though maybe it's true Debian can afford the increased bandwidth.

It's possible to use it, but the tradeoff can be significant.  I know that
we couldn't use it routinely at Stanford, since our Mailman server is
already running pretty much flat-out with the lists that we have and the
increased traffic load would result in serious user-noticable delays.

One of the problems with Mailman for large installations like ours (over
20,000 mailing lists, many archived, many with very large messages with
attachments, some with huge numbers of subscribers) is that it's hard to
cluster multiple systems in Mailman.  Too much of the data assumes a
single writer, particularly for archiving.  So you can't easily
horizontally scale by just throwing more systems at the problem.

The large message with attachments problem is particularly bad and one
that Debian doesn't really have in the same way.  We have users who send
multiple MB Word attachments to mailing lists with a thousand subscribers,
most of whom are all at the same recipient MX servers.  Duplicating those
messages per subscriber is significant.

All that being said, I don't consider this single issue sufficiently
severe to argue against including qmail in the archive.  I find it very
annoying, but it falls short of being actively broken IMO.  A few more
qmail sites in the world realistically isn't going to make that big of a
difference to the problem of unparseable bounces, and qmail is *far* from
the only offender.

Russ Allbery (rra@debian.org)               <http://www.eyrie.org/~eagle/>

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