Newsgroups: comp.mail.uucp
Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!umich!terminator!doom.ifs.umich.edu!honey
From: honey@doom.ifs.umich.edu (Peter Honeyman)
Subject: rerouting to an absolute address
Message-ID: <1990Aug7.081953.6108@terminator.cc.umich.edu>
Sender: usenet@terminator.cc.umich.edu (usenet news)
Reply-To: honey@citi.umich.edu (Peter Honeyman)
Organization: Center for Information Technology Integration, Univ of Michigan
References: <1990Aug6.230109.4220@ibmpa>
Date: Tue, 7 Aug 90 08:19:53 GMT

Steve DeJarnett writes:
>From: steve@qe2.paloalto.ibm.com (Steve DeJarnett)
>...
>	Of course, then we get to the following problem.  apple.sgi.com is a
>FQDN.  Great.  Now the Rabid Rerouters pop up, and say "great, a FQDN very near
>the end of the path (actually, at the end).  Let's short-circuit to that."
>BOING!  If apple.sgi.com isn't Internet-connected, and doesn't have anyone
>MX-ing for it, the mail bounces.  Now, this is a worst-case analogy, but it 
>does happen.  I used to be a proponent of Rabid Rerouting (when I was the one
>modifying the sendmail.cf files on an Internet-connected machine).  Now that
>I sit with an address that looks like it's Internet-connected, but is only 
>connected to a corporate internal network (soon to be rectified with at least
>an MX record, but that's beside the point), I see things in a different light.
>I would love for Rabid Rerouting to work.  However, until every workstation is
>IP-reachable (or at least has a host MX-ing for it), this isn't going to work
>(IMHO).

according to ibm.com, qe2.paloalto.ibm.com is a non-existent domain.  as
david herron put it, your use of domains is very very very very wrong.

your name server must recognize the names that you make, or people and
other mailers that comprehend the domain name system are going to be very
very very very upset with you.

	peter

ps:

i maintain that rerouting in the manner folks have been discussing is good
practice.  to illustrate,

    ^.*!([^!]+\\.)(arpa|edu|com|gov|mil|net|org|[a-z][a-z])(!.+)$

appears in code that runs here.  the stuff not in parentheses -- dot star
bang -- is given the heave ho.  (sites not on the internet could map it to
uunet.)

in practice, this type of rerouting almost always works.  my ua and mta
header mungers do it all the time.  ibm's horrible abuse has been a
problem, but that's soon to be rectified, quote quote.

as for semantics-based rerouting, my experience with pathparse, when i
used it daily, was that it worked very well, but was a hassle to
maintain.  building a dbm file for the 50,000 edges in the usenet maps,
takes too long.  it's also not clear that you can entrust mail to a system
that relies on the usenet maps being timely and accurate.  so i have never
run a rerouter from the mta -- although it can be semantically correct to
do so!

today, i run a right-to-left (so-called rabid) rerouter out of the ua.  i
view the modified address as a hint.  sometimes i change it back.

regarding arpatxt, the hosts.txt -> pathalias hack, a number of prominent
mailer scientists toyed with this, even incorporating it into daily use.
but weeding out conflicts between hosts.txt and the usenet maps is an
all-consuming chore.  (at last count there were over 400 entries in the
"exceptions" list.)

even so, i continue to use arpatxt here.  i don't bother updating the
hosts.txt file.  the result is satisfactory -- it recognizes the
equivalence of the uucp/FQDN names of the well-known gateways -- but it
suffers from the same accuracy/timeliness problems as the usenet maps.