[Gllug] E-Mail screening and reverse DNS

Paul Cupis paul at cupis.co.uk
Sun Jun 11 19:18:10 UTC 2006


Nix wrote:
> On Sun, 11 Jun 2006, Paul Cupis yowled:
>> Ken Smith wrote:
>>> My guess is that the IT dept at the remote site have set up some
>>> rigorous reverse DNS validation. The reverse DNS for here will be
>>> ksmithdsl.claranet.co.uk. So the reverse DNS for my locally hosted
>>> domain won't check out. My outgoing e-mail goes directly and not via
>>> Clara's SMTP server.
>>>
>>> So my question is: how is this dealt with?
>> Fix your reverse DNS so it matches your forward DNS?
> 
> Why should it need to do that? Sites rejecting SMTP connections
> where forward != reverse DNS (as opposed to those where forward and
> reverse do not resolve to the same IP) will reject a very large
> proportion of legitimate mail, including mail from many *major*
> mailing lists.

OTOH I notice that today:

$ host ksmithdsl.claranet.co.uk
ksmithdsl.claranet.co.uk        A       80.168.136.138
$ host 80.168.136.138
Name: ksmithdsl.claranet.co.uk
Address: 80.168.136.138

which matches - the impression I got was that this was not the case when
the OP posted (though I didn't check).

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