Linux Mail-Queue mini-HOWTO

4. Delivering e-mail

E-Mail delivery can be invoked by issuing the command "sendmail -q". For those who are interested in what sendmail actually does, "sendmail -q -v" will give a more verbose version of the delivery process.

It is very convenient to automate the process of e-mail delivery. A tool commonly used for this process is cron.

4.1 How to have e-mail delivered at special times.

Edit your crontab:

crontab -e

Add lines of the form:

05 18-23,0-7    * * Mon,Tue,Wed,Thu,Fri /usr/sbin/sendmail -q
05 *            * * Sat,Sun             /usr/sbin/sendmail -q

Please refer to the crontab man page (available through "man 5 \ crontab") for further information. I think the format is pretty obvious. The example crontab entries shown above send e-mail (if, and only if, e-mail is available from the queue) 5 minutes after an hour on weekdays, starting at 6:05 pm, and stopping at 7:05 am. On weekends, e-mail is delivered 5 minutes after an hour, starting at 12:05 pm on Saturday, and stopping 11:05 pm on Sunday.

As a dial-on-demand user, it is sometimes desirable to have your system collect your e-mail via the POP3 protocol at certain times of the day. You could therefore add an entry similar to the following to your crontab:

0 21            * * * popclient -3 -u <your pop3 user name
goes here> -p <put your password here> -o /var/spool/mail/<the user
on your system that should receive the collected e-mail>
<mailhost.somedomain.com>

Of course, this should all go on a single line.

Then, save the file and leave the editor. The crontab should now be installed.