[Mailman-Users] Mail stuck in Exim queue

[Jim Tittsler]

On Sat, Oct 30, 2004 at 12:57:39PM +0100, Adrian Cooper wrote:
> The solution appears to be to restrict the number of concurrent connections
> between Mailman and Exim. I have added the relevant lines to the Mailman
> configuration but for some reason if I place the recommended line in
> Exim.conf, Exim will not start. The line is:
> 
> smtp_max_sessions_per_connection = 30

That is not a valid Exim option.  You may be thinking of
smtp_accept_queue_per_connection (which defaults to 10, and you
may want to bump up to 30 if you set Mailman to use
SMTP_MAX_SESSIONS_PER_CONNECTION = 30), with
smtp_accept_max_per_connection setting the hard limit (but it
defaults to 1000, which is far more than I feed Exim at a time
from Mailman).

If you really are concerned about the number of *concurrent*
connections, the Exim options you will want to tweak include
smtp_accept_max and possibly smtp_accept_max_per_host.

None of these would leave messages around in the Exim queue
indefinitely though... which I thought was your original
complaint.  You may want to adjust the frequency queue runners
are started (either with -q or with another task) and the
number of simultaneous queue runners (queue_run_max) if you
have the I/O bandwidth to support it.  I use many more than the
default 5 queue runners in a typical installation.

> This is the relevant information as documented in:
> 
> http://www.exim.org/howto/mailman21.html#basic
> 
> And it is nothing to do with cPanel:
> 
> By default Mailman will send up to 500 recipients on each message it injects
> into exim. However this is not necessarily a good configuration for exim
> since it will route all those recipients before starting deliveries to any
> of them. Additionally some ACL configurations have tests on the maximum
> number of recipients (which is a good reason for having a get out ACL for
> list traffic as described above)
> I would suggest setting Mailman to send a maximum of 5 to 50 recipients on a
> single mail (setting it lower decreases list latency, but increases the work
> that Mailman and exim have to do), and change it to send a maximum of 30
> messages per SMTP connection. To reflect this you should also change the
> exim parameter smtp_accept_queue_per_connection to be 30 as well.

Note the name of the exim parameter it recommends.  :-)

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