Unfortunately I dont think all these Spam Filters are infalable...
Many spammers use other innocent parties SMTP/IP to send their crap into the e-mail network...therefore I would think cannot be cross referenced against the DNS black list...
Still if people dont secure there SMTP and Hosting Services continue to host the websites of the spammers! I have been reporting all spam to the site hoster and their communication supplier, in many cases the spam stops however their are some hosting services who just dont care! Most appear to be in the US where the SPAM laws appear inadequate as the offenders cry 'freedom of speech'!!
The messages I love are the 'this is not SPAM because we have provided an unsubscribe link in accordance with Federal Law blah blah' - Bull!!!!! it is unsolicited SPAM!!!
Suggest the answer is with the legislators especially in the US...I understand that many EU countries have already made SPAM illegal including Germany and Holland...this enables controlling action to be taken against both the senders and the hosters...so they then just move across the Atlantic...