--On Thursday, July 8, 2004 5:36 pm +0200 Brad Knowles <[EMAIL PROTECTED]> wrote:
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.
I'm not sure that I follow what you are saying here.
Anyway, exim won't be queueing mail AFTER doing the VERP. Only the un-VERPED message gets queued. EXIM's philosophy is to avoid queueing messages if possible, because it is usually possible to deliver a message at the first attempt. Probably better than 99% likelihood for a typical mix of domains.
Mailman will queue one copy of the message, and exim will pick it up and immediately attempt delivery (including VERP rewrites). If it delivers to all recipients, it throws away the message. If it has temporary failures on some, it will leave the single message on the queue, and write a file recording who has received the message.
At least, I think that's the way it works. The strategy probably wouldn't work with an MTA like qmail which queues first and thinks later.
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 formats.
Of course it does! The whole point of the recipe is to deliver Mailman like VERP without the overhead in handoff of messages from Mailman to the MTA.
-- Ian Eiloart Servers Team Sussex University ITS
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