I downloaded a copy of DeskNow a free email and collaboration server that has mail, file sharing, message boards and calendar functionality. If you register for a commercial licence it also acts as an instant messaging server with jabber compatibility. From what I’ve seen so far it looks pretty good and could make a nice cutdown version of exchange server! One of the good things in the email clients is timelimited emails. By appending the date that you want an email to expire to the username part of the address, email sent after this date will be dropped as spam. ie fred.040302@domain will drop emails after the second of March 2004. Filtering is also available on the server, but again its functionality that you need to register the server for. Still worth checking out if you run a small mail server on an office lan or for home users.