Email · appears in CAIQ, SIG, ISO 27001
Is MTA-STS published to enforce TLS for inbound SMTP?
MTA-STS forces inbound SMTP to use TLS and refuse downgraded connections. Without it, an in-path attacker can strip TLS and read mail in plaintext (SOC 2 CC6.7).
How to answer this
Whichever verdict your domain earns, this is the wording to put in the response box. Reviewers mark an answer down for vagueness more often than for a "No", so say which state you are in and what evidences it.
- Yes
- MTA-STS is published and enforcing TLS for inbound SMTP
- Partial
- MTA-STS is present but not in enforce mode
- No
- MTA-STS is not published for this domain
Controls this evidences
| Framework | Control | Why it maps |
|---|---|---|
| SOC 2 | CC6.7 | MTA-STS prevents SMTP TLS downgrade attacks. |
| ISO 27001 | A.8.24 | — |
| NIST 800-53 | SC-8 | — |
Domain Posture is not an audit and does not replace an auditor. See methodology v1 for how each verdict is reached.
When a "Yes" stops being true
MTA-STS policy removed or moved out of enforce mode (testing/none).
That is the whole problem with answering a questionnaire from a screenshot: the answer was true the day you took it. A signed evidence pack is dated, and a schedule re-checks it so you find out before your reviewer does.