On 2011-01-18 at 17:44 -0500, Seth Dillingham wrote:
> A few times per week the server gets a burst of 1000+ outgoing messages in
> less than a minute. (They're notifications to (paying!) subscribers of a
> newsletter, that a new issue is ready.) I don't understand the behavior very
> well, but exim seems to go into a panic mode where all deliveries are
> deferred while it tries to sort through this mountain of mail.
These would be the configurable limits to avoid bringing the server to
its knees, with options such as "queue_only_load".
> However, without a queue runner, they all just sit there in the queue until
> I run it manually. Our normal load is perhaps 100-200 outgoing messages per
> day, which generally are not queued and just pass through the system very
> quickly.
For processing large batches, you really don't want to have each mail go
through as quickly as possible, concentrating instead on throughput.
So, you should probably start Exim with something like
exim -bd -qq10m
This runs the daemon and starts queue-runners every 10 minutes; the use
of -qq instead of -q causes "two-stage" queue-runs. In the first stage,
no remote deliveries are done, but hints are accumulated; in the second
stage, remote deliveries are done, and because of the hints Exim can
send multiple emails down one SMTP connection.
Most people don't notice the need for the separate flags because their
MTA comes set up by the operating system, and when they switch MTAs,
they look at the existing flags. The use of both -bd and -q<time> is a
Sendmail-ism, also supported by Exim. This is just How It's Done for
Unix MTAs. We try to document this well and *specific* suggestions for
improvement are welcome.
Eg,
----------------------------8< cut here >8------------------------------
-bd
This option runs Exim as a daemon, awaiting incoming SMTP connections.
Usually the -bd option is combined with the -q<time> option, to specify
that the daemon should also initiate periodic queue runs.
[...]
----------------------------8< cut here >8------------------------------
-Phil
