As noted previously, Exim is able to deliver messages immediately or
queue them for later processing. All incoming mail is stored in the
input directory below
/var/spool/exim. When queueing is not in
operation, a delivery process is started for each message as soon as
it arrives. Otherwise, it is left on the queue until a
queue-runner process picks it up. Queueing can be
made unconditional by setting queue_only in the
configuration file, or it can be conditional on the 1-minute system
load by a setting such as:
which causes messages to be queued if the system load exceeds
4.
[1]If your host is not permanently connected to the Internet, you may
want to turn on queueing for remote addresses, while allowing Exim to
perform local deliveries immediately. You can do this by setting:
in the configuration file.
If you turn on any form of queuing, you have to make sure the queues
are checked regularly, probably every 10 or 15 minutes. Even without
any explicit queueing options, the queues need to be checked for
messages that have been deferred because of temporary delivery
failures. If you run Exim in daemon mode, you must add the
–q15m option on the command line to process the
queue every 15 minutes. You can also invoke exim
–q from cron at these intervals.
You can display the current mail queue by invoking Exim with the
–bp option. Equivalently, you can make
mailq a link to Exim, and invoke
mailq :
This shows a single message from [email protected] to two recipients sitting
in the message queue. It has been successfully delivered to
[email protected], but has not
yet been delivered to [email protected], though it has been on
the queue for two hours. The size of the message is 52K, and the ID by
which Exim identifies this message is
12EwGE-0005jD-00. You can find out why the delivery
is not yet complete by looking at the message's individual log file,
which is kept in the msglog directory in Exim's
spool directory. The –Mvl option is an easy way
of doing this:
$ exim –Mvl 12EwGE-0005jD-00
2000-01-30 17:28:13 example.net [192.168.8.2]: Connection timed out
2000-01-30 17:28:13 [email protected]: remote_smtp transport deferred:
Connection timed out |
Individual log files keep a copy of log entries for each message so you can
easily inspect them. The same information could have been extracted from the
main log file using the
exigrep utility:
$ exigrep 12EwGE-0005jD-00 /var/log/exim/exim_mainlog |
That would take longer, especially on a busy system where the log files
can get quite big. The
exigrep utility comes into its own
when looking for information about more than one message. Its first argument
is a regular expression, and it picks out all the log lines concerned with any
messages that have at least one log line that matches the expression. Thus it
can be used to pick out all messages for one specific address, or all those to
or from a specific host.
You can keep a general watch on what a running Exim is doing by running
tail on its main log file. Another way of doing this is to
run the eximon utility that comes with Exim. This is an X11
application that puts up a scrolling display of the main log, and also shows
a list of messages that are awaiting delivery, as well as some stripcharts
about delivery activity.
