What are rDNS issues?

As part of Reputation, we’re always monitoring your IPs and domains for rDNS (reverse DNS lookup) issues. In a nutshell, reverse DNS is the mapping of an IP address to domain name (“point to”, or “PTR”). It’s the opposite of forward DNS, which maps domain names to IP addresses. Our rDNS tool analyzes both forward and reverse DNS to pinpoint issues with your PTR records.

For example, your forward DNS for “” might point to (again, “PTR”), but that doesn’t necessarily mean points to They’re two separate DNS entries, but a rDNS issue nonetheless.

Fixing rDNS issues is important because many receiving mailboxes are instructed to reject incoming mail from any sending IP address that does not have a rDNS record configured. In other words, it directly impacts your deliverability if your rDNS is flawed.

With our tool, we’ll illustrate which IP addresses are not correctly mapped to a domain name, or visa versa, as illustrated here:

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