Here's what I did at an earlier job:
1) Ran Windows Server on a colo box
2) Everyone who had *nix machines could log in into this machine, and run Outlook
3) Setup a filter to *redirect* all email to an IMAP server
4) Setup local IMAP server (or share IMAP server among fellow *nix users)
5) Use any client to talk to IMAP server
This works well if there's more than one person with this situation, so you can share the Windows and IMAP resources. But that requires Windows Server, to allow multiple people to be logged in at the same time.