Reverse DNS / PTR Lookup
Look up an IP's reverse DNS (PTR) record, a common factor in mail server reputation and deliverability.
Forward-confirmed DNS (FCrDNS) means the PTR resolves back to the same IP: the gold standard for mail reputation.
Related: run a forward DNS lookup on the hostname.
This check is sent via DNS-over-HTTPS to Cloudflare, with Google and NextDNS as fallbacks.
Learn about reverse DNS (PTR) records
What a PTR record actually is
Reverse DNS is the inverse of a normal A record. Instead of mapping a domain to an IP, a PTR record maps an IP back to a hostname, published in a special reverse zone. Mail servers check it specifically because a missing or mismatched PTR record is one of the oldest and simplest signals for spotting spam-sending infrastructure.
Reading your results
A PTR record that resolves to a hostname matching your mail server or ISP is a good sign. A missing PTR, or one that doesn't roughly match forward DNS in both directions (often called forward-confirmed reverse DNS, or FCrDNS), is a common reason mail gets rejected or flagged, especially from a self-hosted mail server.
Common questions
Why does my home internet connection have no PTR record? Most consumer ISPs don't set customer PTR records to anything meaningful, and generally don't allow customers to run mail servers from home IPs at all. That's expected, and only matters if you're actually trying to send mail from that address.
I set a PTR record, but mail is still getting rejected. Why? Check that it matches forward DNS in both directions. The hostname your PTR record points to should itself resolve back to the same IP address.
Who actually controls my PTR record? Whoever owns the IP block, which usually means your hosting provider or ISP, not your domain registrar. You typically request a change through their support team or control panel rather than your own DNS zone.