Mail PTR Records

[Peter Farrow]

Matt Kettler wrote:
> mikea wrote:
>> On Mon, Mar 03, 2008 at 01:15:21PM -0600, Nathan Olson wrote:
>>> It's not RFC-compliant.
>>
>> As has been mentioned elsethread, a number of techniques which are 
>> increasingly necessary for survival are not RFC-compliant.
>> Many RFCs were written when the Internet was kinder, gentler, and MUCH
>> less dangerous than it is now. They have not changed, though the 'Net
>> certainly has. Blind adherence to them in the face of evidence that 
>> that adherence opens windows of vulnerability is not necessarily dood
>> or wise.
>
> Well, that alone isn't a good reason to blindly toss RFC's aside. Some 
> requirements of the RFCs are there for damn good reasons.
>
> However, in this case I suspect the activity isn't even a violation of 
> an RFC, and not having a PTR record clearly violates their 
> recommendations (albeit not their requirements).
>
> In general, it's really easy to claim something isn't complaint with 
> the RFCs without any evidence to support it. We should all take such 
> suggestions (including those generated by me) as unsubstantiated 
> opinions until proven otherwise..
>
>
>
>
>
http://tools.ietf.org/html/rfc1912

Its an RFC to have a matching forward and revserse DNS lookup, so not 
having one or a mismatched one is a violation of RFC1912

To quote, verbatim,

"Every Internet-reachable host should have a name. The consequences of 
this are becoming more and more obvious. Many services available on the 
Internet will not talk to you if you aren't correctly registered in the 
DNS. Make sure your PTR and A records match. For every IP address, there 
should be a matching PTR record in the in-addr.arpa domain."

So you can legitimately bounce the email if the sending host has bad 
forward/reverse DNS...

Regards

Pete