🚀 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

From RFC 976:

2.1  Hybrid Addresses

   There are (among others) two major kinds of mailing address syntax
   used in the UUCP world.  The a!b!c!user ("bang paths") is used by
   older UUCP software to explicitly route mail to the destination.  The
   user@domain ("domain") syntax is used in conformance to RFC-822.
   Under most circumstances, it is possible to look at a given address
   and determine which sort of address it is.  However, a hybrid address
   with a ! to the left of an @, such as a!b@c, is ambiguous: it could
   be interpreted as (a!b)@c.d or a!(b@c.d).  Both interpretations can
   be useful.  The first interpretation is required by RFC-822, the
   second is a de-facto standard in the UUCP software.

   Because of the confusion surrounding hybrid addresses, we recommend
   that all transport layer software avoid the use of hybrid addresses
   at all times.  A pure bang syntax can be used to disambiguate, being
   written c.d!a!b in the first case above, and a!c.d!b in the second.
   We recommend that all implementations use this "bang domain" syntax
   unless they are sure of what is running on the next machine.

   In conformance with RFC-822 and the AT&T Message Transfer
   Architecture, we recommand that any host that accepts hybrid
   addresses apply the (a!b)@c.d interpretation.

---

There you go -- RFC 976 tells you that

	a!b@c	->	@c:a!b

amidst whining about not using hybrid addresses at all. :-)

>And what of:
>
>	b%a@c
>
>Is there a standard which addresses this?  Are most sites giving
>@ higher precedence, or !?

RFC 1123, Section 5.2.16:

---
              An embedded source route is sometimes encoded in the
              "local-part" using "%" as a right-binding routing
              operator.  For example, in:

                 user%domain%relay3%relay2@relay1

              the "%" convention implies that the mail is to be routed
              from "relay1" through "relay2", "relay3", and finally to
              "user" at "domain".  This is commonly known as the "%-
              hack".  

---

------------------------------------------------------------------------------
kevin@cfc.com 		  	  | Kevin Darcy, Unix Systems Administrator
...heifetz!cfctech!kevin 	  | Technical Services (CFC)
Voice: (313) 759-7140 		  | Chrysler Corporation
Fax:   (313) 758-8173 		  | 25999 Lawrence Ave, Center Line, MI 48015
------------------------------------------------------------------------------

In article <1992Nov11.171241.20094@news.acns.nwu.edu> skrenta@casbah.acns.nwu.edu (Rich Skrenta) writes:
>In other words, which is it:
>
>	a!b@c	->	@c:a!b
>	a!b@c   ->	@a:b@c

According to RFC822 and RFC976, the only correct interpretation is @c:a!b.

>And what of:
>
>	b%a@c
>
>Is there a standard which addresses this?  Are most sites giving
>@ higher precedence, or !?

b%a@c is @c:b%a.  According to RFC1123, a!b%c@d is @d,@c:a!b.  However,
this renders the % character useless in the UUCP zone.
-- 
	tron |-<=>-|		ARPAnet:  veritas!tron@apple.com
      tron@veritas.com		UUCPnet:  {apple,pyramid}!veritas!tron

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