Re: [exim] Maximum Outbound SMTP connections...???

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Author: Philip Hazel
Date:  
To: Eric Goforth
CC: exim-users
Subject: Re: [exim] Maximum Outbound SMTP connections...???
On Tue, 30 Jan 2007, Eric Goforth wrote:

> I have just finished looking through all of the specifications for
> exim.conf and can't find an option to limit the number of overall
> outbound connections.. Is there one?


There is no single control for this because Exim operates in a
distributed manner using multiple independent processes.

> Our system sends in huge waves (like 200 at a time), but I only want it
> to deliver a max of 20 simultanously...


1. Set queue_only - then all incoming messages will wait on the queue
until a queue runner finds them.

2. Set a limit on the maximum number of queue runners - each one will
deliver one message at a time. Arrange to start them fairly
frequently.

3. Set remote_max_parallel - this limits the number of connections a
single message delivery makes in parallel.

If you allow 4 queue runners simultaneously, and set remote_max_parallel
to 5, you should never have more than 20 outbound connections. But you
may often have less if messages have fewer than 5 recipients. Tweak the
numbers as you wish.

-- 
Philip Hazel            University of Cambridge Computing Service
Get the Exim 4 book:    http://www.uit.co.uk/exim-book