Ken Simpson wrote (on Fri, Aug 11, 2006 at 09:09:33AM -0700):
Weighing in with an opinion, as bad as blacklists *may be*, at least they let the sender know something's up. Not in an artful way, to be sure, but they give some notice. The sender can do _something_, including dropping his association with the recipient b/c it's not worth his time and trouble. Blackholing email because you think it's spam, OTOH, is pure evil.
Host type can only be used as a relatively small weighting factor toward blocking connections. However in the absence of any other reputation data on a particular IP, it's a safe way to trigger throttling or rate limiting.
IMHO receivers have a right to filter traffic in any way that reduces abuse while serving the needs of their end users. There is a lot of pressure from end users and legitimate email senders to ensure that whatever blocking strategy is in use ensures that the good stuff is not blocked.
I agree that IP by itself is of limited usefullness. My main point was that, however you came to your decision ("today I'm not accepting SMTP from hosts with the number nine in their IP"), you should reject mail you don't want, not accept it and toss it. -- _________________________________________ Nachman Yaakov Ziskind, FSPA, LLM awacs@ziskind.us Attorney and Counselor-at-Law http://ziskind.us Economic Group Pension Services http://egps.com Actuaries and Employee Benefit Consultants