Lotus Notes (works with Linux) (Score 1)

Last year, my company migrated from Exchange to Lotus Notes/Domino. (Domino is the name of the server product, Notes is the name of the client). Migration of data from Exchange to Notes was fairly easy. The best thing was the server runs on Linux, Solaris, and all IBM mainframes. Of course, Windows 2000/2003 Server are supported, but I prefer not to purchase CALs. For 50 users, I think we spent $3000. That included webmail, pop3 server, imap server, everything. I really don't think Notes gets the credit it deserves sometimes. Did I mention that it doubles as a development environment, where you can build applications fairly easily? Good luck!