PTR (Reverse DNS) is needed so that mail servers can check the ip address from where the the e-mail is coming against the hostname which is set in the emails headers. This is a very important step against fighting spam messages. Please find the step to Add and Delete PTR records as follows:

Note : To add a PTR make sure your VPSie has an FQDN configured.

Adding PTR Record: Here you can choose which VPSie and IP address you want to select for the PTR record creation by selecting a VPSie and IP address from the drop-down menu labeled “Select a VPSie” and “Select an IP” then pressing the “Add PTR Record” button.