Reverse DNS Lookup

Reverse DNS (rDNS) maps an IP address back to a hostname. When your mail server connects to Gmail, Outlook, or Yahoo, they check if your sending IP has a valid PTR record. If it does not, your email may be rejected or flagged as spam.

Forward-Confirmed reverse DNS (FCrDNS)

FCrDNS goes one step further: the PTR hostname must resolve back to the same IP address. This proves that the IP and hostname are legitimately associated. Many mail servers require FCrDNS to accept email.

Best practices

• Set a meaningful PTR hostname like mail.yourdomain.com, not a generic ISP hostname.
• Ensure the PTR hostname resolves back to the same IP (FCrDNS).
• Contact your hosting provider to set PTR records — they are configured on the IP owner's side, not in your domain DNS.