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