Filtering based on domain reputation has the same problem as trying to filter based IPv6 address reputation. They can easily change thier domain name at any tim

Filtering based on domain reputation has the same problem as trying to filter based IPv6 address reputation. They can easily change thier domain name at any time, and most spam operations do it every 15 minutes or so. This also has a secondary problem for legitimate domain buyers. If the domain name they buy was previously used for spam that reputation will affect thier business for quite a while. There's actually a market where people buy domains with bad reputations, setup small legitimate businesses and get the reputation cleaned up, then sell the site domain and business for a substantial profit because a site with a good reputation history and established line of business will show up higher on internet searches.