Korreio is GUI to mail systems management based on LDAP, CYRUS and POSTFIX. Its has some integrated modules: a LDAP manager, Cyrus-IMAP Mailbox (cyradm replacement), Cyrus-IMAP Partition manager (report-like), Sieve manager, Postfix Queue manager.
Great tool for Administering OpenLDAP, Postfix and Cyrus-IMAP. I have been using this for the past three years. Hats off to Reinaldo de Carvalho.
This software is great. Really good for Expresso Livre users for example.