Xref: utzoo comp.mail.sendmail:871 comp.mail.misc:2054 Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bbn!bbn.com!rsalz From: rsalz@bbn.com (Rich Salz) Newsgroups: comp.mail.sendmail,comp.mail.misc Subject: Re: sigh (was Re: Short-circuiting a route) Message-ID: <1888@prune.bbn.com> Date: 6 Jul 89 01:07:20 GMT References: <562@daitc.daitc.mil> <12167@polyslo.CalPoly.EDU> Followup-To: comp.mail.misc Organization: BBN Systems and Technologies Corporation Lines: 39 The rule for MX stuff is that once it leaves the Internet, you're on your own. You stuff it back into the Internet, you've got problems. One common problem is possible mail loops. Rewording Paul's article (which is just explaining the same thing that happens with UCAR/Fido, which started this whole chain): ]Decwrl is the MX for KG6KF.AMPR.ORG; it forwards the mail to Vixie for ]delivery. "It creates a path like ] vixie!noe!kg6kf.ampr.org!callsign%callsign" ]If there weren't a direct decwrl->vixie connection, there would be ]problems. (BTW, does it really use a % hack? Ick...) Damn straight. By advertising an MX record you're taking it out of the Internet, but now you're worried about what will happen if you interject it back into the Internet system. >The Moral: don't short-circuit. Wrong. The Moral: don't put full domain names into email paths if they're going through the Internet and you don't want them short-circuited. Hack the path to be something like noe!packet_radio!kg6kf_ampr_org!callsign!callsign >I'd better say it again, several times, since people always mix this up: > if you don't like the paths people use, change the source mailers If you shoot mail into the Internet with a fully-qualified domain name in the address -- yes, Paul, even if it's in the Path line -- than you should expect people to follow it. UUCP host names don't come with an enforceable central naming authority, but domain names do. If you don't want to use them, CHANGE YOUR GATEWAY CODE! /r$ -- Please send comp.sources.unix-related mail to rsalz@uunet.uu.net. Use a domain-based address or give alternate paths, or you may lose out.