Mxtoolbox is a third party tool that enables you to check the DNS records of your domain. This tool is very handy as a webmaster if you wish to establish or look up DNS records and other such domain health analysis report.
Reverse DNS does not contain the hostname
The reverse DNS record is also known as the PTR record, pointer record or IP resolver. A PTR is a reverse record for an IP address which allows an IP to map to a domain and vice versa.
You can think of the PTR record as an opposite of the A record. While the A record points a domain name to an IP address, the PTR record resolves the IP address to a domain/hostname.
That means you can make hostgator.com point to 10.0.0.1 and make a PTR record so that 10.0.0.1, if checked, would tell you that it belongs to hostgator.com. It lets the receiver of your emails check for possible spoof emails which will be treated as spam. Without this record, the receiver must rely on guessing if your email might be spam.
Generally, when you have a PTR record, your emails have a better chance to deliver to the recipient’s inbox instead of the spam folder.
To fix this error, add this record to your DNS zones:
Site IP | PTR | mywebsite.com.
When making changes to DNS, please keep the following in mind that they are not instant; they require time for propagation. Most records need 0-4 hours, but nameserver records require approximately 24-48 hours.