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Path: utzoo!utgpu!water!watmath!clyde!rutgers!ames!hao!gatech!seismo!mcvax!enea!liuida!lel
From: lel@liuida.UUCP
Newsgroups: comp.mail.misc
Subject: Re: Precedence in network mail addresses
Message-ID: <559@smidefix.liu.se>
Date: Fri, 15-May-87 15:18:28 EDT
Article-I.D.: smidefix.559
Posted: Fri May 15 15:18:28 1987
Date-Received: Sat, 16-May-87 21:03:22 EDT
References: <588@bsu-cs.UUCP> <958@xanth.UUCP>
Sender: lenlo@smidefix.liu.se
Organization: CIS Dept, Univ of Linkoping, Sweden
Lines: 66
Summary: Conformance, please.

In article <588@bsu-cs.UUCP>, dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
> The solution is trivial though it would need a change in most
> software.  Introduce symbols that allow you to group address
> components.  I have used parentheses above, but they are already
> taken.  Perhaps square brackets could be used.

The solution is NOT to introduce more symbols.  There are many enough
already, thank you.  What is needed is the conformance to a single
standard, whenever possible, and for the Mail Transfer Agents to
otherwise do intelligent full translations from the transmitting net's
standard to the receiving net's.

In article <958@xanth.UUCP> kyle@xanth.UUCP (kyle jones) writes:
> What we DO need are some rules on how to interpret the wild mixes of the
> non-standard operators such as "%", "!", and "::".  The precedences we use
> here are "@ then "!" then "%".  "::" is a horror from some network of which
> we're (apparently) not a member.  Also I've seen addresses with "@!" and "!@"
> in them.  Any ideas on what to do with these???

OK, let's see:
   "!" is used as a routing operator in the UUCP world.
   "%" on top of "@" is a de facto routing operator in the ARPANET world.
   "::" is a routing operator for VAX/VMS mail.
   "!@" can appear on RFC822 routes embedded in UUCP paths, as in:
	node!node!@domain,@domain:user@domain

Let's then assume that you are a Domainist, ie. you will give "@"
precedence before "!" by parsing routes like:
   node2!node1!user@node3
as:
   node3 -> node2 -> node1 -> user

Now, since "%" is the natural routing operator on top of "@", an
address like:
   node1!user@node2
that is autorouted through "node3" will probably end up looking as:
   node1!user%node2@node3
meaning:
   node3 -> node2 -> node1 -> user

Giving "!" priority over "%" is clearly an error in this case.  However,
if you have a "!" path address ending with a "user%node", you can safely
prioritize "!" over "%", since this cannot be interpreted as a domain
address.  Thus,
   node3!node2!user%node1
should be read as:
   node3 -> node2 -> node1 -> user

One thing that *could* complicate this, is VAX/VMS mail that uses "%"
as special operator delimiting a "Foreign Mail Protocol" from the host
name, as in:
   PSI%24020010040403::LISBET::L-LOVSTRAND
meaning:
   to host 24020010040403 using the Packet Switched Interface, then
   -> LISBET -> L-LOVSTRAND

Fortunately, I haven't seem much of them on the net.  Their forwarding
MTAs seems to be intelligent enough to properly translate them into the
receiving net's standard.  I just wish more MTAs would do the same thing
with "!" addresses going into domain land...

Oh well, just wishing.
--Lennart
(Or perhaps not, see "Electronic Mail Addressing in Theory and Practice
 with the IDA Sendmail Enhancement Kit" being released to you on this net
 (very) shortly)