I still think that it causes problems for mailing lists.
I understand the proposal to be based on the envelope sender, not the sender in the body. Hence, mailing lists work, because they are the envelope sender, not the person who submitted the mail to the mailing list.
numerically speaking, most mailing lists are simple exploding forwarders on par with a sendmail "aliases" entry. in this case the envelope sender won't change at forwarding time, and this would cause a problem if it were possible to repudiate mail sources. such mailing lists would have to change from list: person1, person2, ... to list: "|sendmail -flist-request person1 person2 ..." list-request: postmaster and that's what http://www.vix.com/~vixie/mailfrom.txt means when it says This could scale poorly and may add pressure toward transport remailing (with a new envelope) rather than transport forwarding (reusing the old envelope.)
If that is not the case, then Paul needs to be hassled until the wording is clear that mailing lists will continue to work.
i don't think sendmail.cf code fragments are equivilent to IOS command line fragments. in other words nothing from this thread can be cut and pasted into mr. bush's router (or anybody else's router). there are other lists which are way more appropriate than nanog@ for discussion of spam, and even the mailfrom proposal. i mentioned it not because it needed a hearing -- it had already been heard on those very other lists i mentioned -- but to demonstrate that the most powerful force on the internet is someone who says something won't work. thank y'all for your help in the demonstration. -- Paul Vixie