Sendmail, 3rd Edition

Process Alternate Queues

The sendmail program provides the ability to use queue directories other than the one listed in the configuration file’s QueueDirectory option (QueueDirectory). Other queue directories can be used to solve an assortment of problems. One example is a site being down for an extended period. When a lot of mail is sent to such a site, messages collect in the queue and eventually start timing out. By moving those messages to a separate queue directory and processing it at a later time (when that site is back up), unnecessary bouncing of mail can be prevented.

Note that the QueueDirectory option is not safe. If its value is changed by anyone other than root, sendmail runs as an ordinary user.

Handling a Down Site

If a site is down, messages to that site can collect in the queue. If the site is expected to be down for a protracted period of time, those queued messages will begin to time out and bounce. To prevent them from bouncing, you can move them to a separate queue directory. Later, when the down site comes back up, you can process that separate queue.

There are two ways to move mail to a holding queue. One way is to simply move them to a different directory, but you cannot do that if you are using queue groups. The other way is to use queue groups, as we show later.

Move mail with qtool.pl

If you are not using queue groups, you can move the affected messages to a separate queue using the contrib/qtool.pl script supplied with the sendmail source. If you are ...