purpose of PTR record ?

[Kevin Darcy]

Rob Mortimer wrote:

>On Mon, 01 Dec 2003 23:19:40 -0500, Andrew <andrew at arda.homeunix.net>
>wrote:
>
>  
>
>>PTR records map IP addresses to names, thus doing the reverse of A records.
>>
>>One use of PTR records that is being used more and more nowadays is to 
>>verify the identity of mail servers before mail is accepted from them. I 
>>know of more than one ISP that will not accept inbound mail from any 
>>host that does not have a PTR record.
>>
>>The degree of extra security this provides is debatable, but people are 
>>doing it nonetheless.
>>
>>Andrew
>>    
>>
>
>The RFC for mail servers requires a reverse record. 
>
Pardon me, but which RFC would that be?

>As the authority
>for the PTR record resides with the ISP (owner of the IP address) and
>not the owner of the domain name this allows those of us that run mail
>servers to destinguish between a fully configured mail server and some
>muppet useing an SMTP engine to by-pass his ISP's mailserver to send
>SPAM from an ADSL connection in his bedroom. This assumes that the ISP
>does not set reverse records for it's dynamicly allocated IP address
>pool.
>
>NB Join any campain for revese MX records NOW. 
>
I don't know what a "revese MX record" is, so I'm certainly not going to 
campaign for such a thing.

Please don't be so blinded by your dislike of spam that you'll grab at 
any mechanism you can that seems like it _might_ reduce spam _somewhat_. 
Poorly-thought-through anti-spam measures will cause more damage to 
Internet communications in the long run than spam itself will.

- Kevin