Our requirements are thus: 1. Seamless (or nearly seamless) integration with Outlook
2. Good webmail. 3. Integration with AD 4. Ability to scale beyond 100 users 5. Price Right now the only thing killing Exchange is that you need to buy the server OS, and a bunch of Exchange CAL's. --- Although not exchange oriented, IMail is a damn good product that does interface with AD. That's what I ended up using at VSL. Their new version supports all the stuff that you want: http://www.ipswitch.com/products/collaboration/index.html
