[Mailman-Users] Mailman speed

Brad Knowles brad.knowles at skynet.be
Thu Jul 8 17:36:48 CEST 2004

At 3:52 PM +0100 2004-07-08, Ian A B Eiloart wrote:

>  The MTA does need to VERP remote deliveries, and that means making
>  callouts to remote machines for each recipient. However, exim will
>  use a single connection for each remote host - rather than one per
>  recipient. So, exim has to send the data several times, but it doesn't
>  have to read the data several times.

	The real cost here is not reading the data several times, or 
making several remote connections when one would have sufficed -- 
proper connection caching and queue sorting would have solved the 
latter problem anyway.

	No, the real cost here is the extra queue entries that the MTA 
would have to make for each of the VERPed recipients as received by 
Mailman, as opposed to being able to make just one queue entry and 
allowing the MTA to VERP the recipients itself.

	Synchronous meta-data updates are the single biggest performance 
limiter for MTAs, assuming you have configured the rest of the mail 
server correctly.

>  Yes, it will. There would not have been much point doing it otherwise.
>  The ONLY change to the Mailman configuration there is
>  VERP_DELIVERY_INTERVAL. The exim recipe does the

	Of course, this does assume that the MTA uses the same VERP 
format that Mailman would have used, otherwise Mailman is likely to 
get very confused.  This may or may not pose a problem for you, but 
you should at least check to make sure that they both use the same 

Brad Knowles, <brad.knowles at skynet.be>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.

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