Mail PTR Records

[Peter Farrow]

Richard Frovarp wrote:
> Peter Farrow wrote:
>> 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
>>
> What does "should" mean? should vs shall vs must isn't always the same 
> thing.
The meaning is blindingly obvious to me...