sendmail, 4th Edition

From the Command Line

The -q command-line switch, invoked without a time interval argument, is used to run sendmail in queue-processing mode. In this mode, sendmail processes queues once and then exits. This mode can be run interactively from the command line or in the background via cron(8).

Other command-line switches can be combined with -q to refine the way queues are processed. The -v (verbose) switch causes sendmail to print information about each message it is processing, and to process multiple queues sequentially. The -d (debugging) switch can be used to produce additional information about the queue. We’ll discuss the -v switch as it applies to the queue later in this chapter. Those -d debugging switches appropriate to the queue can be found in Table 15-3 on page 536.

V8 sendmail allows variations on -q: -qI allows you to specify a specific message identifier for processing; -qR allows you to specify specific recipient addresses for processing; and -qS allows you to specify specific sender addresses for processing.^[189]

Process the queue once: -q

The -q command-line switch, without an interval argument, tells sendmail to process the queue once, and then exit. As such, this switch is a handy administrative tool. When the queue fills unexpectedly between queue runs of the daemon, for example, the -q command-line switch can be used to force an immediate queue run:

# /usr/sbin/sendmail -q

When multiple queues are run this way, they are all processed in parallel (Processing multiple ...