I totally agree. No kind of filtering (and I have significant experience in this) works to stop spam. I already said this on nanog, in my opinion we need to develop system that allows ISP mail servers to identify and certify each other (most likely though chained certificates, like its been proposed for secure BGP) and all end users need to use ISP mail servers and always authenticate themselve before sending email. This way, no spammer would be able to get email to directly from his dialup and since certificates would also contain contact information, it would make a lot easier for postmasters to identify and stop any flow of spam that happens. Another solution that has been proposed is SMTP callback. Instead of sending email directly, mail server connects to another and provides its name and reference for the email and receiving mail server then makes callback to pickup that email. This way majority of dialup false-header spam would also be stopped although I think spammers will still find a way around this by using dynamic dns and in general callback system is is less secure then full authentication of all email. > Maybe it *is* time to develop technical solutions that will assist the legal > ones being deployed. > It is certainly useful to think beyond mail, here -- automated unsolicited > communications on your IP-phone will be even more of a problem than with mail. > > Gruesse, Carsten --- William Leibzon Elan Communications Inc.