cleaning out trash bins

wondering if there is some program out there to help clean out trash bins....

I've been running this command to get a list of trash bins sorted by size:

du -sk */Maildir/.INBOX.Trash/cur | sort -n

then manually changing to each box...

cd kathryn/Maildir/.INBOX.Trash/cur

and using rm *

I'm just thinking there must be a better way... Most of our users (800 of them) use Squirrelmail so there is no auto-clean function.