[Mimedefang] DNS and MX records

[Jan Pieter Cornet]

On Wed, May 10, 2006 at 02:13:14PM -0700, Matthew.van.Eerde at hbinc.com wrote:
> > It was described in a now-expired ietf document
> > draft-delany-nullmx-00.txt, still available at:
> 
> How about
> 
> MX 1 nomail.example.com.
> 
> ? Since this does not resolve (nomail.example.com is not a valid
> domain, and never will be), mail being sent their should result in
> immediate rejection, no?

A better suggestion was given in one of the mailing list threads,
to use something like:

domain.tld. MX 0 _not_valid_for_email.domain.tld.

(or a similar special string instead of "_not_valid_for_email"). Since
this would come from the nameservers for domain.tld. itself, any software
trying to resolve the domain would only hit those same nameservers again,
and nothing else, since it was already cached.

However, unfortunately, there was no generally agreed upon new standard
chosen. Another current practice that I see a lot, used by domains that
are for sale (as indicated by the nameserver records), is to use the non-
existing name "dev.null." as the only MX record (see for example:
"fdfw.com", a random example from our logs). That has the same
disadvantage of hitting the root nameservers as ".", though.

-- 
Jan-Pieter Cornet <johnpc at xs4all.nl>
!! Disc lamer: The addressee of this email is not the intended recipient. !!
!! This is only a test of the echelon and data retention systems. Please  !!
!! archive this message indefinitely to allow verification of the logs.   !!