Re: What changes would you make to stop spam? - United Nations Paper

[Marc Perkel]

Theo Van Dinter wrote: On Tue, Aug 01, 2006 at 04:07:38PM -0400, Rosenbaum, Larry M. wrote: A reliable DUL list would be good. If it were possible to determine if an incoming STMP connection were coming from a server or an end user, that might help get rid of the problem of spam from zombie PCs, which seems to be a big part of the spam we get. Perhaps ISPs could be persuaded to publish this information. A possibly better method is to block SMTP outbound from the ISP. There was a paper at LISA '05 IIRC about dynamically blocking outbound SMTP based on connection rates. Something about how infected/spam relay hosts have a large number of connections/min but real users tend to send only a very low amount of mail per minute, and the ones that legitimately send more can be whitelisted. I think that end users shouldn't be using SMTP at all. I think SPTM should be a server to server protocol and that the POP/IMAP protocol should be modified to allow sending outgoing email over the same connection that mail comes in over. That way the sender is someone who has verified that they are also the recipient.