I would like to trap and then use the absence of a Host name in ACL
Connection.

      condition = ${if and{ {def:sender_host_address} \
                   {!def:sender_host_name} } {yes}{no} }

The above condition, found on the Internet, can not discriminate between
the absence of a host name and the absence of a Reverse DNS entry.

On Sat, 2014-08-23 at 14:37 +0100, Jeremy Harris wrote:

> >> What are you defining as "absence of a host name" ?

> > A look-up using the sender's IP address produces:  3(NXDOMAIN) 

> A lookup of what, in what?
>
> It sounds a bit like a Reverse DNS lookup to me...
> If that's what it is, how are you defining the difference
> between "absence of a host name" and "absence of a Reverse DNS entry"?

I wondered if Exim can define the difference between

(a)  the sender's host IP address not having a look-upable name; and

(b)  the sender's host IP address' name not having a look-upable IP
address.

The above condition does not distinguish between the two related but
different states.


-- 
Regards,

Paul.
England, EU.

   Centos, Exim, Apache, Libre Office.
   Linux is the future. Micro$oft is the past.


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