immediate deletion of read mail

[Charles Whitaker]

We're in the process of moving to Mac OS X Server 10.4.5. For 
historical reasons, most of our 700+ mail users use POP to get their 
mail. We'd like to configure Cyrus to immediately delete messages 
after downloading -- but not for all mailboxes. The utilities ipurge 
and cyr_expire have been suggested, but they don't seem to 
distinguish between messages that have been downloaded and those that 
haven't. Thanks to whoever can help.
-- 

Charles Whitaker