Incoming SMTP in the year 2017 and absence of DKIM

Thu Nov 30 17:03:24 UTC 2017

> On Nov 30, 2017, at 1:22 AM, Bjørn Mork <bjorn at mork.no> wrote:
> 
> "John Levine" <johnl at iecc.com> writes:
> 
>> Broken rDNS is just broken, since there's approximately no reason ever
>> to send from a host that doesn't know its own name.
> 
> rDNS is not a host attribute, and will therefore tell you exactly
> nothing about the host.

It tells you something about the competence of the operator and
whether the host is intended by the owners to send email.

Or, for a more empirical way to look at it, there's reasonable correlation
between having missing, generic or incorrect reverse DNS and the host
being a source of unwanted or malicious email.

Cheers,
  Steve