Sendmail, a question on Forwarding host

[Paul H. Hargrove]

In article <3591 at lamont.ldgo.columbia.edu> dale at lamont.ldgo.columbia.edu (dale chayes) writes:
>
>I have discovered that occasionaly my local sendmail configuration is
>causing problems at my "forwarding host" by creating an odd address.
>So I poked around with sendmail -v and observed a bit of (what seems
>to me to be) strange behavior shown in the example below.
>
>hp8c is an unknown host, 
>lamont is my "forwarding host"  from the DF & CF macros in sendmail.cf

Dale expects sendmail to change 'dan at hp8c.nrl.navy.mil' into
>dan%hp8c.nrl.navy.mil at lamont.ldgo.columbia.edu
>
>but instead, it creates [...]
>[...] <@lamont.ldgo.columbia.edu:dan at hp8c.nrl.navy.mil>

Well, believe it or not, Dale, this is the correct result.
This address means send the mail to dan at hp8c.nrl.mil via
the host lamont.ldgo.columbia.edu which is just what you
told it to do when you defined lamont as your forwarding
host.

If the mail is not being delivered for some reason, it is
not because of this line (unless lamont is not recognizing
it correctly).

Dale's confusion at this result is not uncommon.  It was actually
expected, as the following excerpt from RFC 821, which defines the
SMTP, shows:

>August 1982                                                      RFC 821
>Simple Mail Transfer Protocol                                           
>
>
>
>   3.6.  RELAYING
>
>      The forward-path may be a source route of the form
>      "@ONE, at TWO:JOE at THREE", where ONE, TWO, and THREE are hosts.  This
>      form is used to emphasize the distinction between an address and a
>      route.  The mailbox is an absolute address, and the route is
>      information about how to get there.  The two concepts should not
>      be confused.                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^
      ^^^^^^^^^^^
For clarification 'forward-path' refers to the recipient (from a To:,
Cc:, or Bcc: line) as opposed to the 'reverse-path' which is the From:
line on the transmitted message.  It does not relate directly to the
kind of forwarding we're concerned with here.

In Dale's case  lamont is a relay host (a forwarding host) so the mailer
on his IRIS sends the mail to the unknown machine (hp8c.nrl.navy.mil) to
lamont using the syntax above.

The result is equivalent to what Dale had expected (which would also
do the job.)

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