MTA-STS policy does not list your mail servers
CODE REDWhat it means
Your policy omits the offending value, which is a live MX host for example.com. Under enforce. Senders refuse to deliver to a host the policy does not cover, this configuration rejects your own inbound mail.
How to fix it
Add an mx: line for every host in your MX records. A wildcard may only replace the leftmost label, e.g. mx: *.mail.example.com
Check your own domain
This page describes the condition. To find out whether your domain has it, run the MTASTS test or the full checkup, which examines every record at once.
Understand it properly
This page covers one condition. For the whole picture, MTA-STS, defined, or start at the Health Library.
Where this comes from
We judge this against RFC 8461 section 4.1. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.
Other MTASTS conditions
MTASTS_MX_MISMATCH
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.