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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!mtuxo!mtunh!mtung!mtunf!ariel!vax135!cornell!uw-beaver!tektronix!hplabs!sdcrdcf!trwrb!trwrba!cepu!ucla-cs!wales
From: wales@ucla-cs.UUCP
Newsgroups: net.mail,net.mail.headers
Subject: Re: Handling %'s and forwarding mail
Message-ID: <6286@ucla-cs.ARPA>
Date: Tue, 9-Jul-85 18:42:18 EDT
Article-I.D.: ucla-cs.6286
Posted: Tue Jul  9 18:42:18 1985
Date-Received: Sat, 13-Jul-85 12:58:40 EDT
References: <226@harvard.ARPA>
Reply-To: wales@ucla-cs.UUCP (Rich Wales)
Distribution: net
Organization: UCLA Computer Science Department
Lines: 35
Xref: watmath net.mail:915 net.mail.headers:497

Kevin Crowston  asked what to do with an address
such as the following:

		xyz%cshost.csnet@csnet-relay.arpa

The correct thing to do is his proposed answer #1.  Namely, open an
SMTP connection to CSNET-RELAY.ARPA and, at the appropriate point, say:

	    RCPT TO:

CSNET-RELAY.ARPA then has the responsibility to worry about interpreting
the address and forwarding the mail to the "cshost.csnet" machine.

The person who replied to Kevin's article by saying that the sending
host should transform the address into  is mistaken.
The sender should not make any effort whatsoever to break down or inter-
pret the "local part" of an address (i.e., the part to the left of the
at-sign); that is exclusively the province of the destination host.

To quote from RFC822, Section 6.2 (page 27):

	The domain-dependent string [i.e., the "local part" of
	the address] is uninterpreted, except by the final sub-
	domain; the rest of the mail service merely transmits
	it as a literal string.

While it is the case that CSNET-RELAY.ARPA happens to use "%" to denote
a "subnetting" operation (as do several other hosts), this convention is
NOT part of the official addressing standard and should NOT be hard-
wired into an outgoing mail handler.
-- 
Rich Wales // UCLA Computer Science Department // +1 213-825-5683
	3531 Boelter Hall // Los Angeles, California 90024 // USA
	ARPA:   wales@UCLA-LOCUS.ARPA  -or-  wales@LOCUS.UCLA.EDU
	UUCP:   ...!(ihnp4,ucbvax)!ucla-cs!wales