[Mimedefang] Domain canonifyin g and RFCs

[Ernst du Plooy]

Steffen Kaise wrote:

> Sorry, I mixed up with the original situation; bind barks if the MX points
> to a CNAME, but the original question was a CNAME pointing to MX/A records.

Yes, I believe it is governed by RFC 2181 section 10.3

10.3. MX and NS records

   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.
   Currently those will be A records, however in the future other record
   types giving addressing information may be acceptable.  It can also
   have other RRs, but never a CNAME RR.