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Re: Do domains in SMTP have to exist ?

2008-04-12 17:34:35

John Levine <johnl(_at_)taugh(_dot_)com> wrote:

Over in DKIM land there is a battle going on with respect to the
treatment of domains that don't exist, with "don't exist" meaning
something like an authoritative DNS server doesn't return an MX or A
or AAAA or CNAME for the name.

   I'm guessing you mean the thread containing

where you wrote:
] 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. 

which, in fact, comes from section 2.3.5.

Looking through the current draft, it looks to me like everyone
assumes that domain names have to exist, with the explicit exception
of the HELO/EHLO name, but it never says so in so many words.

   This language is also found in RFC 2821 Section 3.6; and it does,
IMHO, say that a domain which does not exist in the DNS is out-of-spec.

   However, I see no plausible reading of this text to _require_
testing for the existence of a domain, which is what I believe the
DKIM WG was hoping for.

   (OTOH, it _would_ seem to legitimize any existence-testing that
the DKIM WG might require as _part_of_ using the DKIM protocol.)

Is this a deliberate omission, or is it so obvious that it wasn't
worth stating explicitly?

   I most seriously doubt that consensus could be found to _require_
such testing as part of 2821bis.

John Leslie <john(_at_)jlc(_dot_)net>