[dns-operations] Trustworthiness of PTR record targets

Doug Barton dougb at dougbarton.us
Tue Mar 4 18:28:03 UTC 2014

The OP specifically said "anti-spam providers" in the context of "is 
there a risk that the target domain could be blacklisted by anti-spam 

I am assuming that everyone here (including the OP) knows that specific 
anti-spam solutions that you would run on your mail servers look for 
valid PTRs, but that would seem to be a different thing entirely from 
what the OP seems to be asking about.

... so I revert to my original point, which is that it's hard to answer 
the OP's question intelligently without knowing more about what he's 


On 03/04/2014 10:06 AM, WBrown at e1b.org wrote:
> Doug wrote on 03/04/2014 12:48:03 PM:
>> 2. In my experience (which is not thorough, but also not zero) anti-spam
>> folks are completely uninterested in what's in the PTR, and generally do
>> not do any blacklisting by domain name in the sense you seem to mean.
> Not exactly true.  Many insist that there is a valid PTR record.  Some
> care that it has a valid name, and that the forward lookup for that name
> matches.
> RBLs however, only look at IP address.
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