🚀 go-pugleaf

In article <1992Nov11.171241.20094@news.acns.nwu.edu> skrenta@casbah.acns.nwu.edu (Rich Skrenta) writes:
>I used to think that a!b@c meant "give the message to a with address
>b@c" (Perhaps that's what smail 2.5 did?).  Lately I've been seeing
>lots of address binding @ the other way:  "deliver to c with address a!b".
>
>In other words, which is it:
>
>	a!b@c	->	@c:a!b
>	a!b@c   ->	@a:b@c

Here's the problem:  sites running stock uucp mail (i.e. what AT&T sold
at least up to SysVr3) never look past the first !.  They will thus
send such an addres to site "a" which will interpret the remaining part
"b@c".  There is no provision for changing this behaviour without
replacing the mail transport program on these machines. (Smail is one
such replacement).
In spite of this, the internet standard is to deliver to the site to
the left of the @ sign letting that machine interpret the remaining
part, so a machine running SMTP would deliver to site "c", giving it
the remaining address "a!b".   So you can't use this kind of address
unless you know which machine has which kind of mailer.  What's worse
is that the internet standards demand addresses to be in the
user@domain form and uucp mailers don't provide them.  Thus the
uucp->internet forwarder must provide a return address like:
 uucp!path!user@forwarder.domain
which is fine within the SMTP realm, but when the message is passed
back to a uucp site the headers are generally not modified again
and will probably be misinterpreted. 

>And what of:
>
>	b%a@c

This notation was introduced to avoid the problem of mixing ! and @. 
On the uucp side it's best to use RFC 976 notation - i.e 
hop1!hop2!hop3!domain!user, since it doesn't require knowledge of the
type of mailer used by the intermediate sites and it is understood
by virtually all uucp->smtp gateways.  Unfortunately nothing works
reliably the other direction.  Most internet mailers are of the
opinion that if you don't have a domain name you don't exist, regardless
of the evidence to the contrary.

Les Mikesell
  les@chinet.chi.il.us