Re: [exim] timing for large numbers of recipients

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Auteur: Philip Hazel
Datum:  
Aan: Phil Chambers
CC: exim-users
Onderwerp: Re: [exim] timing for large numbers of recipients
On Wed, 26 Jan 2005, Phil Chambers wrote:

> I am concerned about handling 20,000 users in one go.


So would I be!

> I have set "batch_max = 1000" on the LMTP transport.
>
> Will the SMTP transport sending from the list server to the cyrus
> server time out?


Depends on how fast the cyrus server will accept such a message. You
can, of course, adjust the timeout on the transport.

> As I understand it, exim normally delivers "on the fly" when a message
> is received by SMTP for local delivery (LMTP appears to be a local
> transport). Does batch_max alter that so that the SMTP session closes
> straight after the DATA phase or does the session wait until all
> deliveries have completed?


There is no difference at all between what you call "on the fly"
delivery and a "from the queue" delivery. Your concept of an "on
the fly" delivery is erroneous, I'm afraid.

For ALL messages that it receives, Exim writes the message to disk,
checks that it is safely written, then sends the acknowledgement to the
sender. In other words, the DATA phase ends as soon as the message is
safely received. (The only exception is if you set the mua_wrapper
option, which I assume you will not be using in these circumstances.)

If it is to start an "immediate delivery", it then starts up a delivery
process for that message. If not, it does nothing. In this case a
delivery process is started at some later time by a queue runner. The
actual delivery proceeds in an identical manner in both cases.

> Perhaps I need to set queue_only in a data ACL when there is a large
> number of recipients.


That will make no difference for a single message. It might make a
difference if there are a lot of similar messages at the same time,
because it will have the effect of serializing their delivery.


-- 
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