Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!ames!ptsfa!vixie!paul From: paul@vixie.UUCP (Paul Vixie Esq) Newsgroups: comp.mail.misc,comp.mail.uucp Subject: Re: whether to prefix myhost! onto the From: or not.. Message-ID: <621@vixie.UUCP> Date: Sun, 10-May-87 03:21:19 EDT Article-I.D.: vixie.621 Posted: Sun May 10 03:21:19 1987 Date-Received: Mon, 11-May-87 04:36:44 EDT References: <16238@amdcad.AMD.COM> <600@vixie.UUCP> <748@mcgill-vision.UUCP> Reply-To: paul@vixie.UUCP (Paul Vixie Esq) Followup-To: comp.mail.uucp Organization: Vixie Enterprises, San Francisco Lines: 61 Xref: mnetor comp.mail.misc:275 comp.mail.uucp:532 In article <748@mcgill-vision.UUCP> mouse@mcgill-vision.UUCP (der Mouse) writes: >In article <600@vixie.UUCP>, paul@vixie.UUCP (Paul Vixie Esq) writes: >>In article <16238@amdcad.AMD.COM> bandy@amdcad.UUCP (Andy Beals) writes: >>>[just tack on host! and use rmail and] [M]ail will go through >>>because it's worked this way for years. > >> Mail *may* go through because of all the people between you and your >> mailee who are running broken and non-standard software. > >Is software "broken" because it accepts some things which do not >Conform to the Standard? (Note: "accepts", not "does".) We are having a communication problem, I think. If u1@a sends mail to u2@d, and the mailer decides to route the message as b!c!d!u2 because 'd' is a UUCP site and b!c!d is the shortest path... First, let's say that a, b, and d all conform to the RFC pseudo-standards, and do not modify 'From:' addresses, but that 'c' is running some mailer that prepends hostname! onto the front of the address in the From: lines. Further assume that of all these hosts, only 'a' has an autorouter running. Last, let's leave operator precedence out of this for a moment, and assume that h!u were acceptable in place of u@h. Ok? So, at each host, the From: address LEAVES THE MACHINE looking like this: host From: From_ ---- ----- ----- 'a' a!u1 a!u1 'b' a!u1 b!a!u1 'c' c!a!u1 c!b!a!u1 'd' c!a!u1 (n/a) When u2@d tries to REPLY to this message, the mail will bounce back from 'c' since 'c' doesn't speak to 'a'... "Bad system name: 'a'". Note that the From_ line is in *fine* shape, usually. Replying to that will usually work well, if inefficiently. Gateways can be a pain, too, but on the whole: it will work. If the From: line would just arrive in it's original form, and the replying machine (either the final destination or some complainer along the path) can do a path lookup on the From: address and send the mail back. If it doesn't run an autorouter, it can use the From_ address. Since the From: line will normally arrive bungled and mangled, direct routing will usually not work, and autorouting to the first (or last) host in the path is very likely to result in more bungling and mangling. So, yeah, you can accept non-conforming mail and do constructive things with it -- without violating the spirit of the standard. I don't know what the standards say you are supposed to do with evil addresses -- but I personally feel that an evil address should be stopped where discovered, and sent home to momma to get dressed right before being sent out into the world. Yes, this would result in more mail being returned undeliverable even than occurs in the current mixed-mode mailing scheme we have -- but we would see more mailers standardized in less time under such a policy than under any other I've heard suggested. -- Paul A. Vixie {ptsfa, crash, winfree}!vixie!paul 329 Noe Street dual!ptsfa!vixie!paul@ucbvax.Berkeley.EDU San Francisco CA 94116 paul@vixie.UUCP (415) 864-7013