Zimbra is mail server application. It is opensource mail server having community version and network edition (license version-paid version).
Because of its extreme simplicity and high efficiency. It brings super flexibility to organizations in areas such as email management, dealing with contacts and calendars and handling other associated features such as sharing and managing documents.
Zimbra email hosting services also offer desktop synchronization and mobility. You can access emails and data from anywhere and using any machine.
The software consists of both client and server components, and a desktop client. Zimbra also provides native two-way sync to many mobile devices. It synchronize mail, contacts, and calendar items with open-source mail clients such as Evolution and also with proprietary clients such as Microsoft Outlook.
For details please visit : Zimbra Official