MTA-STS combines DNS and HTTPS
The _mta-sts TXT record advertises a policy identifier. The corresponding policy file is served over HTTPS at mta-sts.<domain>/.well-known/mta-sts.txt.
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MTA-STS checker
Check the MTA-STS DNS record, hosted HTTPS policy and MX coverage.
Your result will appear here.
Run the check to see structured findings, severity, evidence and next steps from the public diagnostics API.
The details
MTA-STS combines DNS and HTTPS
Policy MX names must match
An enforce policy asks supporting senders to use TLS when connecting to the MX hosts listed in the policy. Confirm that the list covers every active mail exchanger before enforcing.
A result is a point-in-time check
DNS can vary by resolver and change over time. Verify important changes with your DNS provider and mail platform. Public DNS checks cannot see every private report or sending configuration.
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What does the MTA-STS checker do?
Check the MTA-STS DNS record, hosted HTTPS policy and MX coverage.
Do I need an account?
No. This public tool is available without registration.