ytnef is a program to decode TNEF streams (winmail.dat). Unlike other similar programs, it can also decode meeting requests and create VCal entries for easy import. It can also create vCard entries from contact cards and vTodo entries from task entries. It also has a Perl script that can be used in procmail recipes to automatically reformat incoming mail appropriately.
The ZideStore server is a native client integration server for OpenGroupware.org. Users can access the contact, appointment, and task database using Outlook, Evolution, and almost any iCalendar compatible client (such as Apple iCal or Mozilla Calendar). In addition, ZideStore supports WebDAV to make the OGo document stores accessible for MS Office and OpenOffice.org.
Zimbra is a next-generation enterprise messaging and collaboration system. It features an Ajax Web client with conversation views, fast email search, Web service mash-ups, shared calendars, document authoring, and IM. The server also syncs to MS Outlook (via MAPI), the Apple desktop (via iSync, iCal, and CalDAV), POP/IMAP clients, and mobile devices (BlackBerry, smart phones, HTML Web browsers). A version of the Web client, Zimbra Desktop, also works offline with any POP/IMAP server. Administrators can control live backup/restores of individual or groups of mailboxes, hierarchical storage (HSM) and clustering, LDAP directory configuration, Web services integration with existing enterprise applications, and integrated anti-spam and anti-virus.