*BSD News Article 85045


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From: kyle_jones@wonderworks.com (Kyle Jones)
Newsgroups: comp.mail.sendmail,comp.mail.smail,comp.unix.bsd.freebsd.misc
Subject: Re: Sendmail vs. Smail...
Date: 17 Dec 1996 19:21:56 -0500
Organization: Wonderworks Inc.
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References: <57tf61$gq7@raven.eva.net> <1996Dec1510.41.00.4656@koobera.math.uic.edu> <1996Dec16.152941.1706@isac.hces.com> <1996Dec1721.54.58.11342@koobera.math.uic.edu>
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 > > So tell us, please, why does the RCPT cost so much time?
 > 
 > [...partial explanation...]

RFC 1854 (aka the PIPELINING spec) is an attempt to standardize a
version of SMTP that reduces the number of response waits in the
session.  If you support PIPELINING and don't do DNS lookups of
any hosts presented to you in the SMTP session, and don't do
IDENT lookups RCPT addresses, you will go a long way toward
reducing the delays.

With regard to multi-RCPT performance in the face of routing
flaps: Routing flaps are often the result of overloaded routing
hardware.  In this scenario, having a connection timeout and fail
is not a bad thing.  Even if it means more total traffic, the
traffic is spread out, which will help a temporarily overloaded
router recover.