Se: http://docs.moodle.org/en/Installing_Moodle#Set_up_cron
http://docs.moodle.org/en/Cron
"Set up cron
Moodle's background tasks (e.g. sending out forum emails and performing course backups) are performed by a script which you can set to execute at specific times of the day. This is known as a cron script. Please refer to the Cron instructions."
Hur och var detta görs beror lite på var och hur din Moodleinstallation driftas.
Mvh
Jonas