DNS question, null MX records

Fri Dec 18 13:58:15 UTC 2009

I concur, in fact I see them come in at precisely the wrong order, lowest
preference first in the hopes that we're not running spam filtering on those
particular hosts.

I have found that putting a bogus mx record at lowest preference slows stuff
down though.

One of my services is for a company with about 150 mboxes, and I receive no
less than 1.5mill spam emails a month for it.

-----Original Message-----
From: Paul Vixie [mailto:vixie at isc.org] 
Sent: Thursday, 17 December 2009 11:48 AM
To: nanog at merit.edu
Subject: Re: DNS question, null MX records

Douglas Otis <dotis at mail-abuse.org> writes:

> If MX TEST-NET became common, legitimate email handlers unable to
> validate messages prior to acceptance might find their server
> resource constrained when bouncing a large amount of spam as well.

none of this will block spam.  spammers do not follow RFC 974 today
(since i see a lot of them come to my A RR rather than an MX RR, or
in the wrong order).  any well known pattern that says "don't try
to deliver e-mail here" will only be honoured by friend people who
don't want us to get e-mail we don't want to get.
-- 
Paul Vixie
KI6YSY