At 05:44 24-02-2008, Alessandro Vesely wrote:
The situation is cumbersome, since rfc1035 says nothing on MX
semantics, referring to rfc974. Indeed, the algorithm is explained
in rfc974, but it is "Obsoleted by: 2821", the SMTP being updated.
However, rfc2181 updates rfc1035 and has a section 10.3 "MX and NS
records" where it says
The domain name used as the value of a NS resource record, or part of
the value of a MX resource record must not be an alias. Not only is
the specification clear on this point, but using an alias in either
of these positions neither works as well as might be hoped, nor well
fulfills the ambition that may have led to this approach. This
domain name must have as its value one or more address records.
Thus, it seems it is up to rfc2821bis to be "clear on this point."
See http://www.imc.org/ietf-smtp/mail-archive/msg04337.html for the