Kmail purge and auto expiry

Ok, so I have an IMAP account now, and I need to purge my deleted messages. Is this the "compact" menu item when I right click on the folder? I see in some message from the Debian list that it is, and to make it "automagic" to select something in the KMail setup. Unfortunately, I don't see the "Settings->Miscellaneous->Compact all folders on exit" that's referenced in the Debian post. Second, how exactly does the "Auto Expiry" (right click on folder -> Properties -> Old Message Expiry) function work? I have several high traffic lists set to expire, and they should be expiring and expunged/purged. Unfortunately, I don't see that happening. Any ideas? Thanks eric