Microsoft has cut prices and changed policies for application service providers (ASPs) that host Microsoft Exchange and other applications. The cost of the monthly Subscriber Access License for the hosted version of Microsoft Exchange has dropped more than 25 percent, from $4.39 per user to $3.25. ASPs can either pass the savings along to customers or use them to increase their margins when hosting Exchange.

http://www.microsoft.com/serviceproviders/licensing/default.asp