Newsgroups: news.software.b
Path: utzoo!utstat!news-server.csri.toronto.edu!math.lsa.umich.edu!math.lsa.umich.edu!emv
From: emv@math.lsa.umich.edu (Edward Vielmetti)
Subject: Re: Who pays the bill?
In-Reply-To: merlyn@iwarp.intel.com's message of 1 Aug 90 23:08:58 GMT
Message-ID: <EMV.90Aug1202214@urania.math.lsa.umich.edu>
Sender: usenet@math.lsa.umich.edu
Organization: University of Michigan Math Dept., Ann Arbor MI.
References: <Jul.30.17.57.18.1990.9079@turbo.bio.net>
	<3275.26b54aab@mccall.com> <1990Jul31.211125.11451@mlb.semi.harris.com>
	<818@toaster.SFSU.EDU> <1990Aug1.201232.23136@ccu.umanitoba.ca>
	<1990Aug1.230858.3264@iwarp.intel.com>
Date: 1 Aug 90 20:22:14
Lines: 42

In article <1990Aug1.230858.3264@iwarp.intel.com> merlyn@iwarp.intel.com (Randal Schwartz) writes:

   ....  Or better yet, if I remember correctly, doesn't the
   RFC allow *any* separator character?  So you could put "yourhost*" in
   the path or even "yourhost!!", and the chances of that getting kicked
   back one or two hops after the initial sender (because of rabid
   rerouters :-) are much higher).

The RFC (1036) sez

    This line shows the path the message took to reach the current
    system.  When a system forwards the message, it should add its own
    name to the list of systems in the "Path" line.  The names may be
    separated by any punctuation character or characters (except "."
    which is considered part of the hostname).  Thus, the following are
    valid entries:

                   cbosgd!mhuxj!mhuxt
                   cbosgd, mhuxj, mhuxt
                   @cbosgd.ATT.COM,@mhuxj.ATT.COM,@mhuxt.ATT.COM
                   teklabs, zehntel, sri-unix@cca!decvax

but also

    Special upward compatibility note:  Since the "From", "Sender", and
    "Reply-To" lines are in Internet format, and since many USENET hosts
    do not yet have mailers capable of understanding Internet format, it
    would break the reply capability to completely sever the connection
    between the "Path" header and the reply function.  It is recognized
    that the path is not always a valid reply string in older
    implementations, and no requirement to fix this problem is placed on
    implementations.  However, the existing convention of placing the
    host name and an "!"  at the front of the path, and of starting the
    path with the host name, an "!", and the user name, should be
    maintained when possible.

I don't care to count the number of software implentations that assume
that "!" is the separator character.  [Hint: Lots.]  

--Ed

Edward Vielmetti, U of Michigan math dept <emv@math.lsa.umich.edu>