Return cleanup period MTA option

Transaction logging MTA options:  (integer)
Sites may supply a cleanup script,, which will then be run every time the    runs. Such a script might, for instance, move or rename MTA transaction log files. To only run this site-supplied script on every  th run of the return job, set the value of the  MTA option to  .

See also:
 * MTA transaction logging
 * Transaction logging MTA options
 * Scheduler task options
 * MTA Tailor options
 * Notification message MTA options