[GRLUG] SMTP reverse DNS validation

[Mark Farver]

Not sure what you are saying...did you get more than one result to a PTR
lookup?  Can you paste dig output displaying the condition?

Requiring anything beyond the existence of a PTR record on an incoming
message is problematic.  You can certainly give positive score to a machine
with valid and identical forward and reverse records but many legitimate
senders will not have that.

Mark
On Apr 23, 2015 11:47 AM, "L. V. Lammert" <lvl at omnitec.net> wrote:

> Ran into an interesting situation recently - the reverse DNS entry for the
> SMTP server listed on the MX record was missing the ".com", and was
> therefore be rejected by an email server that checks reverse DNS.
>
> I was going to send their IT chap a report from MXToolbox showing this
> error, but MXToobox did not show the error because the VPS hostname was
> ALSO listed on the reverse DNS and IT was valid.
>
> Has anyone used a testing service that will actually show validity of the
> reverse DNS (i.e. test for the name match)? I would really like to be able
> to show them the problem, but the issue with MxToobox means that is not
> usable.
>
>         TIA!
>
>         Lee
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