On Fri, Mar 17, 2006 at 02:08:18PM -0600, Johnny Hughes enlightened us:
My How-to doesn't cover Courier because it has it's own special mailbox format and does not use normal Linux users. Dovecot does use normal Linux users and the standard maildir format.
I think you mean Cyrus. Courier can use regular linux users with authpam, authpasswd, or authshadow. It uses the Maildir++ format which extends the standard Maildir, but is completely interchangable. See http://www.inter7.com/courierimap/README.maildirquota.html
Matt