Take the 2-minute tour ×  I think this is a simple question with
a simple answer.  Our domain, cory.co.uk, reports a DNS mismatch
when you do and SMTP test on mxtoolbox.com. I think this is
causing issues sending to some addresses/companies.  We have a
PTR: record set for that points to mail2.cory.co.uk, and our MX
record is set to mail2.cory.co.uk which resolves to, so that all
seems correct.  I was told to set the FQDN on our send
connectors (Exchange 2010) to match the MX record which I have
done, but it has not resolved the issue. I am wondering, as we
have a Sophos mail appliance in between the firewall and mail
server, if the mismatch is because it is using the name of the
Sophos appliance?  In which case, would the solution simply be
to set the name of the appliance cluster to mail2.cory.co.uk?
share|improve this question what exactly does mxtoolbox warn you
about? they do some tests which assume your outgoing HELO/IP/PTR
matches your incoming BANNER/MX IP/MX PTR which isn't
necessarily true. –  Gryph