Reverse DNS (rDNS) is used to look up a domain or hostname from an IP address, which is the reverse of a normal DNS lookup. A correct rDNS record is very important for services like email servers, as it helps prevent your emails from being marked as spam.
You can manage the rDNS records for your server's IP addresses in the PowerPanel.
Network -> IP Management.mail.yourdomain.com) into the field.Prerequisite: For your rDNS record to be valid, a corresponding forward DNS record (an A or AAAA record) must already exist. For example, if you set the rDNS for 1.2.3.4 to mail.yourdomain.com, you must have an A record for mail.yourdomain.com that points to 1.2.3.4.