Openmailadmin is a little administration interface to every complete IMAP mail server daemon. It supports every feature IMAP provides, and fits in most MTA configurations. A key feature is the non-standard, generic administration hierarchy which not only seperates "normal users" from "administrators", but enables the mailserver-master to create instances between them. You will be able to let other users create their own sub-users and thus either share a single mail server between different organizations or project your company's employee structure. It excels with features such as regex addresses and folder ACL management.