Email · Fix guide
MTA-STS not detected
- MTA-STS
- Mail Transfer Agent Strict Transport Security
- TLS
- Transport Layer Security
MTA-STS can require supporting mail servers to use trusted TLS when delivering email.
What is MTA-STS?
Mail Transfer Agent Strict Transport Security lets a receiving domain publish a policy requiring supporting senders to deliver email over authenticated TLS to approved mail servers.
What to do next
- Confirm that every MX host supports valid TLS.
- Publish the MTA-STS TXT record.
- Host the policy at the required mta-sts HTTPS address and begin in testing mode.
Useful links
How to verify the fix
Fetch the policy over HTTPS and test delivery to every MX host.
When this result may be wrong
MTA-STS is optional and only relevant to domains receiving email. A DNS record alone does not prove the hosted policy is correct.
Ready to check again?
Check a domain
Run a fresh report after DNS caches and platform changes have had time to update.