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Subject: Re: qmail, from bugtraq
From: Rask Ingemann Lambertsen (rask-postfixkampsax.k-net.dk)
Date: Sun Feb 06 2000 - 16:56:34 CST

Den 02-Feb-00 20:29:52 skrev Dave Sill fĝlgende om "Re: qmail, from bugtraq":
> "Rask Ingemann Lambertsen" <rask-postfixkampsax.k-net.dk> wrote:

>> Running a qmail system out of memory has unusual consequences. When it
>>can't run qmail-remote to deliver messages, it will, depending your luck,
>>the phase of the moon or just sheer randomness, treat many of these
>>delivery failures as permanent failures, and thus bounce the messages. This
>>won't be fixed for as long as DJB is in charge.

> I can't confirm or deny this claim, but I will assert that a system
> vulnerable to memory starvation is poorly configured. It's easy to
> limit qmail's memory usage, and not doing so is irresponsible.

   There are just so many ways you can run a system out of memory. Someone
feeds Netscape a web page. Someone starts emacs. Someone feeds procmail a
message.

>>But who cares, it is just someones email messages, nothing important,
>>nothing to get excited about.

> Whoa, it's not like messages are lost if this happens; they just
> bounce.

   Really? Watch what happens with the bounce message. Qmail immediately
tries to deliver it. Oh rats, we're (still) out of memory, so this one
bounces too. We now have a double bounce which qmail tries to send to the
address configured for double bounce delivery. With the system still out of
memory, the double bounce also bounces, at which point qmail gives up on it
and calls unlink(). The message has now been lost.

   Alternatively, the bounces do get delivered to your automatic mailing
list manager which then unsubscribes half of your subscribers. How nice.

Regards,

/ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻTŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ\
| Rask Ingemann Lambertsen | E-mail: mailto:raskkampsax.dtu.dk |
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