Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site hou3c.UUCP Path: utzoo!linus!decvax!genrad!grkermit!masscomp!clyde!burl!hou3c!ron@brl-vgr.ARPA From: ron@brl-vgr.ARPA Newsgroups: net.mail.headers Subject: Re: "Return-Path" vs. "From" Message-ID: <243@hou3c.UUCP> Date: Tue, 7-Feb-84 10:37:43 EST Article-I.D.: hou3c.243 Posted: Tue Feb 7 10:37:43 1984 Date-Received: Thu, 9-Feb-84 22:32:44 EST Sender: ka@hou3c.UUCP (Kenneth Almquist) Lines: 33 To: Nathaniel MishkinCc: Mark Crispin , Ellis@yale.arpa The confusion factor is minimized by not looking at RETURN-PATH. If you must, configure your mail reader such that the RETURN-PATH lines are deleted. The reason in you case (although I am not certain) is probably one of human engineering. At BRL, for the sake of user friendliness, a user is allowed to specify any return address in his FROM or SENDER line that will legally get the letter back to him (the validation on this is interesting but too lengthy to discuss here). However, the return path is always set to the address that the system determines is the mail invoker really is associated with. This also allows getting around the multiple FROM list problem. For example: I can send a letter with "FROM: Ronald.Natalie@BRL" but the mail system recognizes me as the "ron" user on the BRL-VGR host and my return path gets marked as "ron@Brl-Vgr". RETURN-PATH should probably not be in the header at all, except that mail does get out of the SMTP environment and it's nice to propagate the information along to the non-SMTP environments. The other major use (other than setting return path to null to avoid error messages entirely) is with large mailing lists. If you look carefully at the large lists maintained at BRL (INFO-{MICRO,UNIX,CPM,APPLE}, UNIX-WIZARDS, MSGGROUP). You will find that although these appear to be simple mail exploders (an incoming letter immediately gets turned around and sent out to the list), a transformation occurs. The RETURN-PATH is changed from what it was to the appropriate -REQUEST list. This keeps the list submitters from seeing errors that are beyond their control to fix and forwards them to the people who might be able to fix them who would ordinarily have seen them. -Ron