ZCS is a complete messaging and collaboration Server with an AJAX Web Client. It features Email, Contacts, Calendar, Documents, Instant Messaging, Tasks, plus synchronization to other desktops and devices.

Web client:

- Rich browser based AJAX interface with application-like features such as drag and drop

- Powerful tagging and conversation views to manage multi-gigabyte inboxes

- Comprehensive sub-second search, including within over 200 attachment types, plus saved search folders

- Share and collaborate on any application- inboxes, contacts, calendars, document, and tasks

- Enterprise calendars with global free-busy, including ZCS to Exchange 2003 server

- Author documents online including images, tables and spreadsheets

- Instant Messaging with buddy lists, multiple conversations and archiving

- Zimlets ‘mash up’ third party applications such as maps, CRM, inventory and package tracking in the Zimbra Web Clients

- Standard HTML web client interface for accessibility and legacy browser support

Administration:

- AJAX Admin Console and full Command Line Interface (CLI) to manage ZCS

- Migration wizards for Exchange, Domino, GroupWise, plus standard IMAP migration

- Real time mailbox backup and restore

- Native hierarchical storage management (HSM) and high-availability (HA) / clustering

- Cross mailbox search and discovery with full archiving for regulatory compliance

- Integrated Anti-Spam, Anti-Virus, and Directory Services

- Open web service APIs / REST interfaces

- Fully supports multi-tenancy and delegated administration for hosting and service provider

Zimbra Desktop:

- Zimbra Desktop enables offline access to the Zimbra web experience and aggregates other POP / IMAP accounts on Mac, PC, and Linux desktops (ZCS server not required) 

Other Desktops:

- Native MAPI synchronization to Outlook 2003 / 2007 with full delegate and offline access

- Native synchronization to Apple desktop applications via Zimbra iSync Connector, plus CalDAV support

- Support for all POP3 / IMAP4 Clients 

Mobile:

- Native synchronization to BlackBerry handsets via Zimbra Connector for BlackBerry Enterprise Server (BES)

- Native “over-the-air” synchronization to Windows 5+, Palm, and Symbian OS Smartphones

- Over-the-air synchronization on popular J2ME devices like the Motorola RAZR 2

- Access Zimbra email, contacts, calendar on any device with an HTML capable mobile web browser.

Browser Support:

Microsoft Internet Explorer, Mozilla Firefox, Apple Safari for Microsoft Windows, Apple OS X, and Linux desktops

Server Operating Systems:

Red Hat, SUSE, Ubuntu, Fedora, Debian, rPath Linux, Mac OS X, VMware Virtual Appliance

3rd Party Client Support:

Microsoft Outlook and Entourage, Mozilla Thunderbird, Apple Mail, Apple iCal, Apple Address Book, Mozilla Sunbird, Novell Evolution

Protocol Support:

MAPI, IMAP, POP, XML, HTTP / S, SOAP, LDAP, SIP, VoIP, iSync, RSS, Atom, iCal, CalDAV, WebDAV (beta)

Please refer our services to feel better about these features.