Exchange 2K Can it use DNS to stop SPAM?

There are SPAM black holes in the internet that allow you to use a reverse DNS query to their servers to see if an email is coming from an IP address that is known to SPAM (see http://www.orbz.org or http://www.ordb.org ). They also show you how to use said black holes with *nix email systems but no mention of Exchange. My question is does anyone know how to make use of such a tool in Exchange? Right now I am using the feature that allows me to block SPAM from getting in on the SMTP by blockingthe spamer?s IP, Domain, or Subnet that is provided in Exchange but that requires a great deal of time to add every occurrence of SPAM reported to the System Administrator.

Carlos