[Mimedefang] Mimedefang errors: What might be the cause?

[Jan Pieter Cornet]

On Mon, Jan 16, 2006 at 11:57:56AM -0500, David F. Skoll wrote:
> > define(`confQUEUE_LA', `2')dnl
> > define(`confREFUSE_LA', `7')dnl
> 
> Bad settings.
> 
> Having REFUSE_LA higher than QUEUE_LA is a surefire way to kill your server.
> Most busy SMTP servers are I/O bound, and running in queue-only mode does
> nothing to reduce your I/O load.  In fact, it *increases* it because the

... unless your mailserver's main role is to deliver the messages on
a large NFS attached storage. Then when the storage has temporary
performance issues, it helps to offload it into the queue temporarily.
Provided your local disks are fast enough, of course. That's why we have
QUEUE_LA slightly lower than REFUSE_LA on our incoming mail servers...

The original poster also mentioned:
> > define(`confDELAY_LA', `2')dnl

Ouch. It might be instructive to read some sendmail source that is
related to DelayLA... sendmail not only delays for one second after
each command, but also sleeps N seconds before accept()ing each new
connection, where N is the number of listening ports.

I tried it once, on a server where we happened to have 6 listening
sockets, and the results were nothing short of disastrous because
we have WAY more incoming connections than 1 per 6 seconds. Your usual
N is 2 or 3 (for ports 25, 465 and 587 (smtp, smtps and submission)),
so if you expect more than one connection every 2 or 3 seconds (that's
30 or 20 new connections per minute), then you should seriously
reconsider your use of DELAY_LA.

-- 
#!perl -wpl # mmfppfmpmmpp mmpffm <pmmppfmfpppppfmmmf at fpffmm4mmmpmfpmf.ppppmf>
$p=3-2*/[^\W\dmpf_]/i;s.[a-z]{$p}.vec($f=join('',$p-1?chr(sub{$_[0]*9+$_[1]*3+
$_[2]}->(map{/p|f/i+/f/i}split//,$&)+97):qw(m p f)[map{((ord$&)%32-1)/$_%3}(9,
3,1)]),5,1)='`'lt$&;$f.eig;                                # Jan-Pieter Cornet