# 9 Set up cron

Several Mailman features occur on a regular schedule, so you must set up cron to run the right programs at the right time6.

If your version of crontab supports the -u option, you must be root to do this next step. Add $prefix/cron/crontab.in as a crontab entry by executing these commands:

        % cd $prefix/cron
        % crontab -u mailman crontab.in

If you used the --with-username option, use that user name instead of `mailman` for the -u argument value. If your crontab does not support the -u option, try these commands:

        % cd $prefix/cron
        % su - mailman
        % crontab crontab.in

Warning: If you accepted the defaults for the --with-username option and for the name of the site list, and one of the cron jobs ever encounters an error, the cron daemon will mail the error output to the 'mailman' user and it will most likely be delivered to the 'mailman' site list and possibly not be accepted. For this reason it is a good idea to insert

        MAILTO=user@example.com

or

        MAILTO=mailman-owner

at the beginning of crontab.in before installing it to cause this output to be mailed to a real user or to the owner of the site list or to configure the site list (see section 8) to accept this mail.

#### Footnotes

... time6
  Note that if you're upgrading from a previous version of Mailman, you'll want to install the new crontab, but be careful if you're running multiple Mailman installations on your site! Changing the crontab could mess with other parallel Mailman installations.