As far as your own incoming mail is concerned, you get the same results by either requiring almost every ISP in the world to block outgoing SMTP from almost all of their users, or by using a blocking list that blocks the same users. The blocking list approach preserves the end-to-end behavior of the Internet, and lets the end users decide whose opinions to follow about which Internet users are first-class citizens vs. second-class citizens. Of course, I was planning to write that comparison before the recent complaints about how bad a job SORBS is doing on deciding who to block. :-) But it's still equivalent. If an ISP wants to be "responsible" about preventing untrustworthy users from sending SMTP that bothers people, they can contribute to blocking lists rather than dropping the users' packets, and the blocking lists can provide some convenient mechanism for the ISPs to update them. Where the two approaches diverge is that the recipient-based approaches can also support whitelists, either individually run or shared exception systems such as Habeas or bonded sender things, while the ISP-blocking approach isn't something you can easily override, except by doing tunneling or other protocol-heavy workarounds. Bill Stewart, bill.stewart@pobox.com