BTW, if you want to use the solution for commercial use, you should check the license requirements of the blacklists used (as been add by yourself to the DNSBL lists, as been built in and used by SpamAssassin as well as any additions on adjustments). Some may have a daily hit ratio and require purchasing feeds or rsync data on exceeding the limit, others always require purchase, if you want to sell anti spam services based on their lists.