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

[Mark Andrews <marka () isc org>]

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  The is too much out-of-date stuff on the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 () 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 () isc org