What is it?
This mail deliverability finding means the test captured the message Received header chain. It is informational evidence rather than a failure.
Why does it matter?
The Received chain helps identify the real sending path. SPF, reverse DNS, forward-confirmed reverse DNS, and reputation checks should use the public sending host, not an internal relay, local receiver, or proxy hop.
How to fix it?
No fix is required if the relay path is expected. Review the first untrusted public IP and confirm it belongs to your outbound mail platform.
Received: from mail.example.com (mail.example.com [203.0.113.20])Do not publish raw headers publicly without review. They can contain private hostnames, user addresses, routing details, or other personal data.