Cyrus Imap
From Nuclear Physics Group Documentation Pages
Though it seems that there are other interfaces available (probably more user friendly ones, using web interfaces etc) the way we can configure cyrus-imap is with cyradm.
See: Cyrus System Administration, Chapter 9 of O'Reilly's "Managing Imap". (Yes, this is so complicated, they wrote whole books about it!)
To start talking to cyradm as the administrator you want to execute (on einstein):
cyradm -user cyrus localhost
and supply the password for the usual password scheme for cyrus.