[imp] Automatically purging messages?

[Michael Wing]

Does anyone know if there's a built-in method to automatically purge
messages from the Deleted and Spam folders without the user seeing a prompt
like:

"...is ready to perform the tasks below. Select each operation to run at
this time.  All messages in your "Spam" folder older than 30 days will be
permanently deleted."

Maybe an option to "Prompt before delete" that I'm not seeing?

I can do it at the server-level with a script and a cron job, but I'd like
to do it the Horde/Imp way if it's possible.

Thank you,

Michael