If it doesn't absolutely have to be Open Source / Free Software, take a look at http://www.bynari.com Their Insight product is reasonable, reliable, runs on Linux / UNIX and interoperates with Outlook and a whole bunch of other things. Does everything Exchange does but costs lots less and runs on Linux. I have no affiliation to Bynari, just like their products... -=[ Steve ]=- Mike Nielsen wrote: > Hi there. I make my living bouncing around the Twin Cities setting up > companies (5-100) users with networks and servers and the like. > > As such I have begrudgingly only offered up support for Microsoft products, > with the exceptions of SNAP servers, firewalls, etc. etc. > > For my smaller clients who are on a tight budget I would like to be able > to offer them a messaging server that has much of the same functionality as > exchange. > > Calendar Sharing, contact management, email, task lists... I haven't found > a lot of products out there that meet that criteria. > > I'll continue to peek around Freshmeat but any place you all can point me > would be greatly appreciated.