The software consists of both client and server components, and a desktop client. Two versions of Zimbra are available: an open-source version, and a commercially supported version with closed-source components such as a proprietary Messaging Application Programming Interface connector to Outlook for calendar and contact synchronization.
Zimbra Desktop is a full-featured free desktop email client. Development was discontinued under VMware’s in 2013 but was restarted in February 2014.
The ZCS Web Client is a full-featured collaboration suite that supports email, group calendars, and document sharing using an Ajax web interface that enables tool tips, drag-and-drop items, and right-click menus in the UI.
ZCS can synchronize mail, contacts, and calendar items with open-source mail clients such as Evolution and also with proprietary clients such as Microsoft Outlook and Apple Mail, either through proprietary connectors or using the ActiveSync protocol, both available exclusively in the commercially supported version. Zimbra also provides native two-way sync to many mobile devices Windows Mobile, iPhone, Android etc.