This is not exactly linux-minded. But I'd suggest MDaemon GroupWare.
MDaemon is as very versatile mailserver for Windows and with the
GroupWare add-on you can use Outlook like you would with Exchange.
Shared calenders, address books and e-mail folders through IMAP.
MDaemon is very easy to use and it's not really expensive, especially
compared to Exchange. I'm not familiair with SuSe prices. The great
thing about MDaemon is, you can backup so easily and restore just as
easy too. You will never loose your mail.
