Configure SpamHaus or other RBL provider with Exchange 2007June 10, 2009
Changing Exchange 2007 receive connector timeoutJune 10, 2009
Open the exchange management shell and run the following commands
Run this command to view your current configuration
Get-RecipientFilterConfig | fl
Then run this command to turn on recipient filtering
Turning on this feature will filter recipients who are not in the directory. This can unlload a ton of processing requests from your Exchange server.