On Thu December 3 2015 01:04:30 Michael Howard wrote:
> No, I'm running into problems running rDNS checks. As mentioned above,
> if you put 'mail.pearsoncomputing.net' into the search box at
> 'http://mxtoolbox.com/diagnostic.aspx' you will receive a warning from
> the 'SMTP Valid Hostname' test to the effect that 'Reverse DNS is not a
> valid Hostname'. The explanation of the warning, correctly states that;

rDNS-DNS checks are run on the connecting IP and show no problem
with 192.119.205.242.

The only place I can find mail.pearsoncomputing.net is in the
EHLO.  SMTP HELO checks are notoriously sensitive and performing
FCrDNS (DNS-rDNS-DNS) checks on them is very likely to encounter
problems, is not recommended, and is considered by many postmasters
to violate RFC 2821.

RFC2821 requires only that the SMTP HELO provide a resolvable
name or an address literal.  There is no requirement for rDNS
or FCrDNS and if you do check the name you should allow the
several forms of address literal in order to permit emergency
communication between postmasters in the event of DNS issues.

Where is your Axigen server getting mail.pearsoncomputing.net
if it's not from the EHLO?  And why is it reporting an rDNS
problem when it is actually performing a FCrDNS check? 

//

Tim's setup is similar to yours.  You have two A records
(mail.dewberryfields.co.uk and dewberryfields.co.uk)
mapping to 82.68.201.106 but only one PTR record in the
reverse direction, in your case mapping to
mail.dewberryfields.co.uk.

//

I recommend that you drop HELO/EHLO checks AND that Tim set
his smtp_helo to pearsoncomputing.net.

--Mike