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Subject: Re: Load Restrictions and queuing
From: Greg A. Woods (woodsweird.com)
Date: Sun Sep 10 2000 - 16:24:46 CDT

[ On Sunday, September 10, 2000 at 13:42:43 (-0700), Ronald F. Guilmette wrote: ]
> Subject: Re: Load Restrictions and queuing
>
> Also, Sendmail provides a feature where you can limit the maximum number
> of new incoming connections that it will accept, per second.

Smail has two limits on the number of simultaneously active connections.
The daemon process that's doing the limit keeps count of the number of
connections it accepts. At the first limit it turns on the "queue only"
flag, and the second limit causes all new incoming connections to be
rejected with an immediate "421" response and a connection close.

> Does Postfix have that? If so, how do I enable it?

The "maxproc" specification for the "smtpd" command in the master.cf
file should be the equivalent of the second limit for Postfix, and since
Postfix always effectively only queues incoming messages there's not
really any need for the first limit as implemented by Smail. By default
it seems this number will be '50' in Postfix (which seems even low for
modern server-class machines).

In Postfix something like the second limit is sort of established by
limiting the number of processes doing message delivery ("local",
"pipe", "smtp", etc.).

Brad Knowles' posting just the other day with the title "optimal value
of master.cf" contains other good advice about tuning Postfix. 

-- 
							Greg A. Woods

+1 416 218-0098      VE3TCP      <gwoodsacm.org>      <robohack!woods>
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