A New Internet-Draft is available from the on-line Internet-Drafts directories.
Abstract: “This Internet-Draft proposes an extension to SMTP for an electronic mail equivalent to the real-world “No Soliciting” sign. In addition to the service extension, a new message header and extensions to the existing “received” message header are described.”
See also: Ned Freeds comments on the Internet Mail Consortium SMTP mailing list.
http://www.ietf.org/internet-drafts/draft-malamud-no-soliciting-04.txt