What is a PTR record?
Also called: reverse DNS, rDNS, FCrDNS
A PTR record maps an IP address back to a hostname: it is reverse DNS. Receiving mail servers look up the PTR of the connecting IP and check that the hostname resolves back to the same IP. Google requires valid forward and reverse DNS for every sending IP.
The check has two halves. The IP's PTR names a host, and that host's A or AAAA record must return the same IP. When both match it is called forward-confirmed reverse DNS. A missing or generic PTR looks like a home connection or a compromised machine.
PTR records are set by whoever owns the IP block, usually your hosting provider or sending platform, not in your own domain's DNS. If you send through an email service on a shared IP, they handle it; on your own server or a dedicated IP, you need to ask for it.
The hostname should match the name your server gives in HELO/EHLO. Gmail rejects mail from IPs without a PTR record with a 550 5.7.25 error.
Example
5.113.0.203.in-addr.arpa. PTR mail.example.com. and mail.example.com. A 203.0.113.5: forward and reverse agree.Go deeper
Sources
By SimpleVerifier Team · Last reviewed 2026-10-13 · All 50 glossary terms