SpamAssassin takes care of this for you by automatically downloading new filtering rules. You host the spam filtering software, but the actual rules are out-sou

SpamAssassin takes care of this for you by automatically downloading new filtering rules. You host the spam filtering software, but the actual rules are out-sourced by default. It even includes configuration for multiple DNSBLs, DNSWLs and RHSBLs by default. You can add your own local rules if absolutely necessary too.