Auto Clear Sent PM Messages
 

Auto Clear Sent PM Messages would be a prune hack, that deletes all sent messages from all the sent folders after 30 days. Any idea?! :bunny:

You can cron a script (even a normal shell script would work) that every week or so runs the query:
[sql]
DELETE FROM privatemessage WHERE folderid = [i]folderid for sent messages;
[/sql]
Be sure to always warn your users when stuff might suddently vanish.

Oh, and where should I write the cron jobs?
Not very familiar with them, never worked for me (HiveMail etc.).

You should probably ask your host on how to set up cron jobs. It can vary wildly.

folderid = [i]folderid for sent messages;
Which id is the one by default?