MTA-STS policy file redirects
URGENTWhat it means
The policy URL answers with a redirect, and senders must not follow redirects when fetching a policy. To every sending server, your policy simply does not exist.
How to fix it
Serve the policy directly at https://mta-sts.example.com/.well-known/mta-sts.txt, no redirect, not even from http to https on that path.
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 3.3. 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_POLICY_REDIRECT
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.