Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!DECWRL.DEC.COM!dcrocker
From: dcrocker@DECWRL.DEC.COM (Dave Crocker)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: MX-registration vs %-hack (was Re: New Host-Requirement RFCs)
Message-ID: <8910251414.AA05270@volition.pa.dec.com>
Date: 25 Oct 89 14:14:14 GMT
References: <7696@ditmela.oz>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 24

I hope that everyone takes note of your simple, but fundamental observation
that use of '%' is a) a legal part of the local-part of an RFC822
address, and therefore b) its use is strictly up to the administrator(s)
of the host that interprets the local-part.  I.e., the host referenced
in the right-hand-side of the address.

The Host Requirements working group spent quite a bit of time considering
whether to make the %-hack a formal part of the document.  We decided that
such a section would formally constrain something that is, by definition,
a matter of local choice. (I suppose we could travel down the road of
analogies, looking at state vs. federal rights, here, but I can't think
of a funny ending to it.)

Use of MX requires formal, inter-organization registration and
maintenance.

Use of the %-hack is a much more localized decision and may be modified
much more easily.

The first makes Internet email users think that you are actually on the
Internet, the latter means that new off-net mail hosts do not need to
be registered in the Domain system.

Dave