ReverseDNS mismatch on domain and hostname

Mauritz

• February 27, 2016 23:00

We have a customer with a dedicated IP address (say 10.0.0.1 and domain is example.com) - The customer has reverse DNS record setup to point 10.0.0.1 - example.com. We want the customer to use their own IP to send mail. We're getting the following errors on mxtoolbox: Reverse DNS is not a valid Hostname Reverse DNS does not match SMTP Banner This, from my understanding, is because the Reverse DNS is pointing to their domain name and not a valid hostname. In this case our hostname would be the same as the cpanel server (example cpanel.host.com) so although the reverse DNS record will resolve to their domain, it will never show to expected hostname as these 2 are different. We have not experienced any real issues even with the warnings from mxtoolbox, but from a customer standpoint we would rather want to give an all clear and change the setup on our end where needed. How would one change this above to work correctly? The reverse dns would never be able to be both the customers domain name (which I suspect is the issue here) as well as "the" valid hostname. I suspect a workaround here is to have a custom hostname to appear during the mailhelo but I'm not sure if it will work the way it should and if this is best practice. We could change the reversedns records to say something like example.host.com but that again would not resolve correctly. Any advice on this above?

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  syslint

  • February 28, 2016 04:07

  You may check the email headers initially and find out which domain name / hostname is showing in 10.0.0.1 . If you want it as the domain name, then correct the DNS and RDNS accordingly. The end user server may be trying to verify the sender as the domain itself and not the hostname. This can be only cleared after getting a detailed header and logfile.

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  cPanelMichael

  • February 29, 2016 15:17

  Hello :) Please ensure you review the following document: How to Configure Exim's Outgoing IP Address - cPanel Knowledge Base - cPanel Documentation I don't believe you can receive a "PASS" score from the third-party utility you are using without changing the RDNS record to point to the server's hostname. Thus, you may want to consider keeping your existing setup in-place, and advising the customer of why it's a false positive from MXToolBox. Thank you.

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