🚀 go-pugleaf

bruce@balilly.uucp writes:
   >	To: user@toaster		To: toaster!user@gatebox
   >	From: me@tinytoy		From: tinytoy!me@gatebox

   The applicable RFC's (including 822) require that addresses on the
   internet must be in domain form (not ! paths), and that fully-qualified
   domains be used.

To clarify that just a bit, the RFCs require that addresses on the
Internet be FQDNs _if_ they are going outside their domain of origin.
Abbreviations within a domain are fine.  RFC822 section 6.2.2 page 29:

        Since any number of  levels  is  possible  within  the  domain
        hierarchy,  specification  of  a  fully  qualified address can
        become inconvenient.  This standard permits abbreviated domain
        specification...

        When a message crosses a domain boundary, all  addresses  must
        be  specified  in  the  full format, ending with the top-level
        name-domain in the right-most field.  It is the responsibility
        of  mail  forwarding services to ensure that addresses conform
        with this requirement.  In the case of abbreviated  addresses,
        the  relaying  service must make the necessary expansions...

The "gatebox" in question is doing exactly the right thing if it is
making addresses palatable to things outside your domain.  If it's
doing it for destinations within your domain, it's harmless but not
especially useful.

If your site inflicts "user@tinytoy" on my sendmail, I'm going to
finish the job of address-breaking that your site started: It's going
to be rewritten as user@cis.ohio-state.edu.  This rewrite does the
Right Thing in the usual case where Joe Random writes mail to, e.g.,
jane@apple.  I have to interpret OneWordHostNames within the context
of cis.ohio-state.edu, a host apple.cis.ohio-state.edu exists, and we
hide hostnames anyway, so I rewrite all OWHNs as cis.ohio-state.edu.

Since a recipient here of address "user@tinytoy" couldn't have replied
directly to it anyway, I figure it serves 'em right if they have to
hunt through Received: headers for the real information they needed.
I post an explanatory "mail/news/finger glitches and solutions" to a
local newsgroup periodically so that the users know what's what.

--karl