From Zarafa wiki
The following scripts give you the possibility to automatically delete all items older than x days in your Junk E-mail folder and Deleted Items folder.
To use these scripts the php-cli package need to be installed. To install & use the script follow these steps:
- Extract the tar to /usr/local/bin
- Set in both the spam.php & deleted.php the option $daysBeforeDeleted to the correct value
- To run the script use the command /usr/local/bin/cleanup
You can put this script in a daily or weekly cronjob to schedule a cleanup action.