How To Fix Reverse DNS Does Not Match The SMTP Banner Error
Security Boulevard, December 11,2025
The 'reverse DNS does not match SMTP banner' error occurs when the domain name in your mail server's greeting message doesn't match its reverse DNS (PTR) record.
This mismatch affects email authentication, often leading to deliverability issues or rejections by providers like Gmail or Outlook.
The reverse DNS ensures your IP correctly maps to your domain, while the SMTP banner identifies your mail server during an email transaction. If these two records don't align, receiving mail servers suspect spoofing or poor configuration.
Understanding and fixing this issue helps ensure your emails pass verification checks, maintain sender reputation, and reach inboxes reliably without unnecessary filtering or blocking.