Doug Otis and I have been working up a proposal for a SMTP extension to shift some of the burden of spam abatement away from the receiving SMTP servers towards the originator. It is now published at:
http://datatracker.ietf.org/drafts/draft-otis-smtp-tbr-ext In essence it holds the originator responsible for maintaining the copy of the message until a receiving Mail User Agent determines that it should be delivered to the recipient. This quite specifically allows reputation-checking to proceed at leisure, not subject to time constraints (except for recipients who demand sub-millisecond delivery of every spam message ;^) It also gives us a "for-free" version of graylisting, in that no further network traffic is needed to enforce a time delay before a message is accepted from an unknown originator. As part of the proposal, we add conditions that ensure a workable return path for Delivery Status Notifications, requiring that the same domain which manages the server from which the message will be fetched also publishes a MX record to receive the DSNs. Obviously, comments are welcome... -- John Leslie <[EMAIL PROTECTED]>
