From: utzoo!decvax!harpo!duke!unc!smb
Newsgroups: net.news.b
Title: Re: return addresses
Article-I.D.: unc.3682
Posted: Mon Jul 12 22:55:16 1982
Received: Tue Jul 13 06:56:27 1982


I sympathize with the problem -- like msc, I often get frustrated by
the reply addresses I see.  The two main problems are non-uucp networks --
ARPA, the BerkNet, etc. -- and "shy nodes", which won't pass on mail to
outside machines, but might be in a netnews path.  The former tends to
be much more serious, especially because of the ARPAnet -- uucp's left-host
convention, and ARPA's right-host convention conflict, and can result in
ambiguous parses -- given the string 'a!b@c', does one send a letter to
host 'c', thence to be passed on to host 'a', or does one send to host 'a',
which in turn will pass it to host 'c'.  There's no way of telling which
machine user 'b' is on.  In our specific case, the ARPAnet link between
SRI and CCA is especially troublesome; a news item can go from hplabs to
sri-unix via uucp, via ARPA to cca, and then via uucp to decvax.  And just
to keep life interesting, cca won't act as a gateway; mail from uucp sites
will not be passed through to the ARPAnet.  (The other cases I know of
where news has a lot of trouble generating a reply address are replies
that go through alice, rabbit, or research -- they're shy -- or letters
that go to teklabs -- their news path goes through ARPAVAX, which is not
a good mail route.)

What can be done about this?  In the short term, not very much.  If you
know a path to the proper host, and you're using ucbmail, you can edit
the 'To' line with ~h.  ucf-cs!tim's or my path-calculators can help,
even if they're only used manually.  (Incidentally, for folks who want
to use mine but can't/won't modify delivermail -- you can use the data
it produces in a front-end processor much like Tim's; it should take about
10 minutes to write one (advt)).  2.7 netnews makes it easier to use
non-standard mailers, since one can set the environment variable MAILER
to the name of your favorite mail program.  And if your mailer lets you
specify the subject field on the command line, you can get that inserted
automatically as well, via something like

	setenv MAILER "/usr/ucb/mail -s '%s'"

for csh users (note the single quotes as part of the string, incidentally).

The long-term answer is to do away with this explicit-routing nonsense
entirely, and enter the brave new world of the Internet.  In it, all
addresses will be of the form 'user@host' or 'user@host.network'.  Clearly,
such a scheme requires a pretty good name table, but at least it gives you
an unambiguous name to work with.  By coincidence, just yesterday I
suggested to the netnews implementors that the next version of netnews
start generating a 'Reply-To: user@host' line in every news item; that
way, by the time folks have mailers capable of dealing with such addresses,
a substantial proportion of the news commands out there in network land
might be generating them.  (The routing data will still be retained; it's
used as an optimization to prevent sending a news item on to a site that's
already seen it.  But it will become strictly left-to-right, with the '!'
assuming the role of a separator character, not a network indicator.)  I've
not yet given much thought to the gateway question -- when should a '.uucp'
or '.usenet' or '.arpa' be tacked on -- but even without that, we'll be
better off than we are now.