Zimbra is open source server and client software for messaging and collaboration - email, group calendaring, contacts, and web document management and authoring. The Zimbra server is available for Linux, Mac OS X, appliances, and virtualization platforms. The Zimbra Web 2.0 Ajax client runs on Firefox, Safari, and IE, and features easy integration / mash-ups of web portals, business applications, and VoIP using web services.
Zimbra is an open source server and client technology for next-generation messaging and collaboration. Zimbra delivers innovation for both the administrator and the end-user as well as compatibility with existing infrastructure and applications (both open source and proprietary).