Victor Duchovni:
> On Fri, Apr 29, 2011 at 09:39:10AM -0400, Wietse Venema wrote:
>
> > > This looks like a Null MX record:
> > > http://tools.ietf.org/html/draft-delany-nullmx-00
> > >
> > > If the domain owner declares that this domain never sends or recieves
> > > email, then shouldn't postfix reject the above message with a permanent
> > > error?
> >
> > Anyone can post a draft. That does not mean that they change
> > the rules of the Internet.
> >
> > The SMTP RFC says that the MX record specifies a hostname, and
> > there is no RFC that says an empty string is a valid hostname.
>
> This said Null MX records are IMHO a reasonably simple/clean idea. Pity
> it never got officially blessed. I seem to recall that same concession
> to Null MX records was made in a Postfix release a while back...
How clean can it be? It requires that an RFC-compliant program must
change from two-valued logic (an RFC-compliant MX record exists or
does not exist) into three-valued logic (no MX record, RFC-compliant
MX record, non-compliant MX record) which leads to cascading code
inconsistency and consequently new bugs.
I think it is bad engineering when take some invalid form and then
give it legitimate meaning. This rewards sloppy programs that play
fast and loose, and punishes programs that enforce the rules.
Wietse
