DNS question, null MX records

Douglas Otis dotis at mail-abuse.org
Wed Dec 16 19:20:16 CST 2009

On 12/16/09 4:48 PM, Paul Vixie wrote:
> 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.

Agreed. But it will impact providers generating a large amount of bounce 
traffic, and some portion of spam sources that often start at lower 
priority MX records in an attempt to find backup servers without valid 
recipient information.  In either case, this will not cause extraneous 
traffic to hit roots or ARPA.


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