A PTR record (pointer record) provides reverse DNS: it maps an IP address to a hostname, the opposite direction to an A or AAAA record. PTR records live in special reverse zones, in-addr.arpa for IPv4 and ip6.arpa for IPv6, and are controlled by whoever owns the IP block, typically your hosting or email provider rather than your domain registrar.
For email, the PTR record is the foundation of reverse-DNS reputation checks. When a server connects to deliver mail, the receiver reads the PTR for the connecting IP and often performs forward-confirmed reverse DNS, checking that the PTR hostname resolves back to the same IP. A missing, generic, or mismatched PTR is a frequent cause of mail being throttled or marked as spam, so it has a real impact on deliverability.
Note that a PTR record is about the sending IP, not your From domain, so it is independent of DMARC, SPF, and DKIM alignment. The historic SPF ptr mechanism, which used reverse DNS for SPF evaluation, is deprecated and should not be relied upon. To fix PTR problems, ask your IP provider to set a meaningful reverse-DNS hostname for each sending IP, then verify it with a PTR or reverse-DNS lookup tool.
Check it on your domain
- PTR Record Checker: a reverse-DNS lookup for an IPv4 address.
- Reverse DNS (FCrDNS) Checker: checks forward-confirmed reverse DNS (FCrDNS) for a mail IP or domain.