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Re: [ietf-dkim] protecting domains that don't exist

2008-04-12 09:12:59
Jim Fenton wrote:
If ADSP can depend on a well-specified requirement for
checking for the existence of the domain, please indicate
where this is specified.

The current 2821bis draft says in sec 5:

   Only resolvable, fully-qualified, domain names (FQDNs) are permitted
   when domain names are used in SMTP.  In other words, names that can
   be resolved to MX RRs or address (i.e.  A or AAAA) RRs (as discussed
   in Section 5) are permitted, as are CNAME RRs whose targets can be
   resolved, in turn, to MX or address RRs.  Local nicknames or
   unqualified names MUST NOT be used. 

The 2822upd draft says in sec 3.4.1:

      Note: A liberal syntax for the domain portion of addr-spec is
      given here.  However, the domain portion contains addressing
      information specified by and used in other protocols (e.g.,
      [RFC1034], [RFC1035], [RFC1123], [I-D.klensin-rfc2821bis]).  It is
      therefore incumbent upon implementations to conform to the syntax
      of addresses for the context in which they are used.

and a little later

   The domain portion identifies the point to which the mail is
   delivered.  In the dot-atom form, this is interpreted as an Internet
   domain name (either a host name or a mail exchanger name) as
   described in [RFC1034], [RFC1035] and [RFC1123].  In the domain-
   literal form, the domain is interpreted as the literal Internet
   address of the particular host.  In both cases, how addressing is
   used and how messages are transported to a particular host is covered
   in separate documents such as [I-D.klensin-rfc2821bis].  These
   mechanisms are outside of the scope of this document.

So the intention is clearly that the domains in addresses are supposed
to exist, but I don't see it in a MUST sentence.  I'll ask whether
that's deliberate, or it was so obvious that they didn't think it was
worth mentioning.

Regards,
John Levine, johnl(_at_)iecc(_dot_)com, Primary Perpetrator of "The Internet 
for Dummies",
Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor
"More Wiener schnitzel, please", said Tom, revealingly.



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