Newbie Question: Is anyone actually using the Null MX (RFC 7505)?

Fri Feb 26 21:53:04 UTC 2021

I think just about everything has been said beyond contacting the operators of the
online testing tools and requesting that they update their tool or to take it down.
A broken tool is worse that no tool.  The is too much out-of-date stuff on the
Internet.  We should all be doing our little bits to correct it or remove it.

Mark

> On 26 Feb 2021, at 21:19, Pirawat WATANAPONGSE via NANOG <nanog at nanog.org> wrote:
> 
> Dear all,
> 
> 
> I put the “Null MX” Record (RFC 7505) into one of my domains yesterday, then those online mail diagnostic tools out there start getting me worried:
> 
> It looks like most of those tools do not recognize the Null MX as a special case; they just complain that they cannot find the mail server at “.”
> [Sarcasm: as if the root servers are going to provide mail service to a mere mortal like me!]
> 
> Among a few shining exceptions (in a good way) is the good ol’ https://bgp.he.net/ which does not show that domain as having any MX record.
> [maybe it is also wrong, in the other direction?]
> 
> I fear that the MTAs are going to behave that same way, treating my Null MX as a “misconfigured mail server name” and that my record will mean unnecessary extra queries to the root servers. [well, minus cache hit]
> 
> So, here comes the questions:
> 1. Is there anyone actively using this Null MX? If so, may I please see that actual record line (in BIND zone file format) just to satisfy myself that I wrote mine correctly?
> 2. Which one makes more sense from the practical point-of-view: having a Null MX Record for the no-mail domain, or having no MX record at all?
> 
> 
> Thanks in advance for all advices,
> 
> --
> 
> Pirawat.
> 

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org