Reverse DNS (PTR) Lookup

PTR (Pointer) records are the reverse of A records — they map an IP address back to a hostname. When a mail server receives an email, it often checks whether the sending IP has a valid PTR record as a basic anti-spam measure.

Forward-confirmed reverse DNS (FCrDNS) is an even stronger check. It verifies that the PTR hostname resolves back to the original IP address. If this check fails, many mail servers will treat the email with suspicion or reject it outright.

If you're sending emails from a server or IP without a properly configured PTR record, your messages are much more likely to end up in spam folders or be rejected. Contact your hosting provider or ISP to set up reverse DNS for your sending IPs.