Zimbra is a Web Client is a full-featured collaboration suite that supports email and group calendars using an Ajax web interface that enables tool tips, draggable items, and right-click menus in the UI. Also included are advanced searching capabilities and date relations. Online document authoring, “Zimlet” mashups and a full administration UI are also included. It is written using the Zimbra Ajax Toolkit.
It exposes a SOAP application programming interface to all its functionality and also is an IMAP and POP3 server. The server runs on many distributions of Linux as well as on Mac OS X.