A reverse DNS lookup is a query that will retrieve the domain associated with a given IP address. It's simply the opposite of the well-known DNS lookup which gives IP addresses associated with a domain.
Reverse DNS lookup is commonly used by email servers to track down malicious messages and spam, as it can identify and verify the domain of an incoming email.
Reverse DNS lookup is a key element of the security protocol used by email servers to protect recipients from malicious emails. Not all sending servers are supporting Reverse DNS lookup, but those that don't are likely to be blocked by receiving servers. This can affect negatively your deliverability, and this is why you should check if your server supports such a protocol.
.png)
.png)