Tony Finch wrote: > On Thu, 16 Aug 2007, Keith Moore wrote: > >> I do think there might be some merit in having designated outgoing mail >> servers for any particular domain, >> > > How do you intend to support forwarding? or do you have in mind something > like CSA not SPF? > I was making a general statement, not a detailed proposal. Offhand I think that forwarding should be traceable - that is, there should be information in the message envelope detailing who or what forwarded the message. For a forwarded message, that person or process would need to be associated with the outgoing mail server. Note that I didn't say it would be easy to fold that into the existing SMTP framework. >> I also think there might be some merit in holding mail on the sender's >> outgoing mail server until the receiver's MX is willing to deal with it, >> thus pushing more of the costs toward the sender of a message. >> > > If I am not sure about the legitimacy of a message, it's better for me > to get as much information about it as possible (i.e. receive the whole > thing) so that my AI has the best chance of producing the right result. > The only case where delaying email might help is when I expect that more > information (e.g. from reputation services) might be available later. In > other cases, delays only harm legitimate email and don't hinder spammers > at all, since spammers have infinite computer resources. > One advantage in having mail stay on the sender's side until delivery is that it enables the sender to reliably determine the status of a message at any time, and to reliably know whether a message were delivered, refused, or bounced. That feedback path would in turn provide incentives for senders to supply reliable indications to recipients that the message were legitimate (so as to encourage recipients' mail systems to process the mail more quickly), and would also let senders know whether such indicators were acceptable to recipients. The purpose of keeping things on the sender side until delivery is not to delay mail, so much as to make mail traceable. Pushing the costs toward the sender is a (mostly) useful side effect. Keith _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf