If you need to change or modify your PTR record on a Contabo server, this article will provide you the necessary steps.
Procedure
First, log into the Contabo customer control panel.
From here, navigate to "Reverse DNS Management," where you can edit your PTR record for your VPS or Dedicated server.
Once you have completed the change, you can verify your PTR record using this article:
Resources
Please see "How to setup PTR (rDNS) records on your cPanel & WHM server" for instructions for other providers.