Zimbra Collaboration Suite

Zimbra Collaboration Suite Publisher's Description:
Zimbra Collaboration Suite (ZCS) 4.0 is modern, innovative messaging and collaboration.-Zimbra is the leading open source solution for enterprise, service provider, academic, and government environments; offering administrators and their end-users unmatched benefits and TCO. Zimbra is popular choice for today's growing-Linux email server base. ZCS features an award-winning Ajax web client integrating email,-contacts, shared calendar, enterprise mash-ups, VoIP, and online document authoring and-sharing. Also included with ZCS is a complete server solution with built in anti-spam, MTA, storage, authentication, and admin features.
The Zimbra Collaboration Suite supports Windows, Apple,-and Linux platforms and works with seamlessly Microsoft Outlook as well as other-PC and mobile device clients. Two versions of ZCS are available: the Open Source Edition and the Network Edition. The ZCS Network Edition is available to download as a free-60 day trial and features many powerful enhancements such as Outlook integration, real-time backup and restore, and mobile device OTA sync.