PTR records are mainly used to check if the server name is actually associated with the IP address from where the connection was initiated.
The usage of a reverse DNS setup for a mail server is a good solution. Some external mail exchange servers make reverse DNS lookups before accepting messages originating from your mail server.
Was this article helpful? do let us know by hitting the thumbs up icon and feel free to share your comments so we may improve our guides for everyone else in Cyber Security Community.