Spamhaus has recently announced a new list called Composite Snow Shoe List (CSS), which is now included in Spamhaus SBL and ZEN. To learn more about the new list and to download the updated definition file, please visit
The goal of the Composite Snow Shoe List is to spam the so called “snow shoe” spammers, who send only moderate amount of junk from a single IP to stay under the radar. They spread the load between multiple IP addresses and domains to dilute reputation metrics and evade filters (just like a snow shoe spreads the weight, hence the name).
Hopefully, the new list will improve your current filtering efficiency even further.