Free desknow software for linux

DeskNow project is a fully featured and easy to use mail and collaboration server that can handle all the communication and collaboration needs of your company.
Main features:
- fully featured mail server
- advanced antispam technologies, antivirus integration and content filtering
- dynamic webmail interface
- document management
- advanced calendaring with meeting planning, free/busy search, shared calendars, task lists, resource booking, iCal publishing (Mozilla Sunbird, Apple iCal)
- Outlook connector to integrate personal and group calendars, tasks, contacts
- SyncML synchronization with Palm, PocketPC, BlackBerry and most mobile phones
- secure Jabber instant messaging with integrated web client
- automatic authentication and account import with Active Directory and LDAP servers
Enhancements:
- This version introduces minor improvements to IMAP import and features improved SyncML duplicate detection and a maxhops configuration setting.