Managing junk mail for RCs?

Guys,

We have a simple RoundCube/IMAP setup for the RCs.  One issue the RCs
often have is that their mailboxes get full of spam between releases.
We've limited the size of the mailboxes to limit this issue.

However, I'm at a loss as to how to tell RCs whose mailboxes are full
how to empty them.  The standard deletion procedure involves moving
messages to "Trash" and then emptying the trash, but that doesn't work
if your mailbox is completely full.    Does anyone know a workaround for
this?

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com