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 220.127.116.11 that points to mail2.cory.co.uk, and our MX record is set to mail2.cory.co.uk which resolves to 18.104.22.168, 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?