In exchange server 2007 ,how can I hold up thelitter mail? echang

I can only assume you're talking about spam when you say "litter mail." Exchange Server 2007 has 2 versions, Standard and Enterprise. Additionally, each user's CAL has 2 different levels, Standard and Enterprise.I believe what you're looking for is the user Enterprise CAL (not to be confused with the server Enterprise license.) See here:http://www.microsoft.com/exchange/howtobuy/default.mspx"The Exchange Enterprise CAL provides access to Unified Messaging and advanced compliance, as well as Forefront Security for Exchange Server and Exchange Hosted Filtering for onsite and hosted antivirus and anti-spam protection."Other than that, you'd have to purchase spam filtering software or a hardware appliance.Maybe someone can correct me if I'm mistaken.