Path: utzoo!attcan!uunet!ncrlnk!ncrcae!ece-csc!ncsuvx!gatech!cwjcc!hal!ncoast!allbery
From: allbery@ncoast.UUCP (Brandon S. Allbery)
Newsgroups: comp.mail.uucp
Subject: Re: active rerouting
Message-ID: <12604@ncoast.UUCP>
Date: 23 Sep 88 21:56:46 GMT
References: <4740@b-tech.UUCP> <4747@b-tech.UUCP> <4748@b-tech.UUCP> <6581@chinet.UUCP> <2105@edsews.EDS.COM>
Reply-To: allbery@ncoast.UUCP (Brandon S. Allbery)
Followup-To: comp.mail.uucp
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 40

As quoted from <2105@edsews.EDS.COM> by roberts@edsews.EDS.COM (Ted Roberts):
+---------------
| In article <6581@chinet.UUCP>, les@chinet.UUCP (Leslie Mikesell) writes:
| > 
| > Suppose
| > you want siteC to route  siteA!siteB!siteC!domain.dom!user or
| > siteA!siteB!siteC!user@domain.dom.
| 
| These are not the same thing.  The first route would send to siteA, then
| siteB, then siteC and siteC would route to user@domain.dom which they
| would know how to do since they know how to resolve domain addresses
| (you hope:-).  The second would attempt to send to domain.dom, then to
| siteA, then to siteB, then to site C, then to user.  This is because the
| "@" syntax takes precedence over the "!" syntax.
+---------------

WRONG!!!  "@" and "!" are used by different networks -- there is NO defined
precedence between them!  (You're comparing apples to oranges.)  UUCP sites
give "!" precedence, Internet domain mailers give "@" precedence.

On ncoast (a UUCP system) "!" has precedence.  Our neighbor "hal" gives "@"
precedence because they are on the Internet.  This can be quite useful; if I
want to send mail across the Internet I can mail to hal!foo@bar.COM, thus
overriding the UUCP route (which may well be slower) that smail would give
me from a straight "foo@bar.COM".  On your system, you would probably want
to switch to UUCP only after you got as "close" to the recipient's system as
possible, so you would want "@" to have higher precedence.  Thus, the
current system is useful for both of us.  Just don't assume that everyone's
mailer handles things the same way, as we *are* on different networks.

Things get even more interesting when you try to apply your rules to a
DecNet network or to the Bitnet as well (on Decnet, does "::" have
precedence above or below "@"?  How about "!"?  Does Decnet even *care* what
the relative precedence of "!" and "@" is?)

++Brandon
-- 
Brandon S. Allbery, uunet!marque!ncoast!allbery			DELPHI: ALLBERY
	    For comp.sources.misc send mail to ncoast!sources-misc
"Don't discount flying pigs before you have good air defense." -- jvh@clinet.FI