1) Zimbra (commercial and free versions available)
- Desktop client compatibility. Sync mail, contacts, and calendar to Microsoft Outlook and/or to Apple (Mail, Address Book, iCal).
- Professional administration. Real time mailbox backup and restore, high availability clustering, storage cost management.
- Zimbra Mobile. Over-the-air synchronization of mail, contacts, and calendar data with mobile devices.
- Advanced web productivity. Ability to search for content inside attachments and view attachments as HTML instead of downloading.
- Domain management. Ability to re-brand the web client and administer multiple customer domains.
2) Open Xchange (commercial and free versions available)
- Linux Compatibility. Support 30 different linux distributions.
- All Information in One folder. Using one folder, users can store all information needed for a particular project, including all contacts, meetings, and background information.
- Document Management. Automatic versioning, locking of documents during editing, saving from MS Office applications, and access from MS explorer.
3) Scalix (commercial and free versions available)
- Outlook Support. Offers automatic offline mailbox caching and improved PDA syncing.
- Plug-in support. Provides certified plug-ins support for Google Desktop and MSN Search, McAfee VirusScan, Symantec Norton Utilities and Captaris RightFax Outlook Extension.
- Search and Indexing Services. Real-time indexing of private and public folder messages. This results in sub-second mailbox-wide search and retrievals, even in very large mailboxes and folders.
- Ajax Support. An intuitive, easy-to-use AJAX interface.
- Domain Management. Multiple domain support.
- Easy Installation. installs in minutes without the need to manually integrate all the different components together.
- Contact Management. Saves and organizes thousands of personal and company contacts, telephone, fax, addresses, e-mail contact addresses just to mention a few. Easily configurable with extensive and speedy search capabilities, categorization and remotely accessible.
- Group Calendar. Manage meetings and events for an entire group or individual set of accounts. Attach notes to appointments. Link appointments to contacts and projects. Automatic detection of conflicts.
- Resource Planner. Keep track of your company’s resources such as automobiles, projectors or conference rooms. Searchable timeslots to check for availability of specific resources or resources assigned to a specific group. Automatically check for resource conflicts upon appointment creation.