Re: [Exim] exim client pipelining

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Author: Philip Hazel
Date:  
To: Marques Johansson
CC: exim-users
Subject: Re: [Exim] exim client pipelining
On Fri, 9 Jul 2004, Marques Johansson wrote:

> Is it possible to configure exim to use pipelining when sending email to
> other servers?


No, because Exim will do so automatically if the server advertises
pipelining. However, you can *stop* it using pipelining by setting
hosts_avoid_esmtp in the smtp transport.

> Would the effect be any different than a client side version of
> 'smtp_enforce_sync false'? Is it known that pipelining is improves
> performance?


1. Yes. The client has to send a whole bunch of commands and then
process the results as they come back, and take note of "expected"
errors (e.g. a rejection of DATA after all RCPTs are rejected is
"expected" and not a real error).

2. I believe so. It reduces the number of TCP/IP round trips,
significantly for small messages. I guess it matters less if all your
messages are M$word monstrosities. :-)

--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book