Email · Fix guide
SMTP STARTTLS needs review
- SMTP
- Simple Mail Transfer Protocol
- STARTTLS
- Start Transport Layer Security
The primary mail exchanger did not advertise opportunistic TLS to this checker.
What does this test measure?
The primary mail exchanger did not advertise opportunistic TLS to this checker.
What to do next
- Confirm port 25 is reachable on every MX host.
- Enable STARTTLS and install a valid certificate.
- Test MTA-STS or DANE only after STARTTLS works consistently.
How to verify the fix
Connect to every MX over port 25, issue EHLO and confirm STARTTLS is advertised.
When this result may be wrong
Some hosts block outbound port 25, so an unavailable result can reflect the checker network rather than the mail server.
Ready to check again?
Check a domain
Run a fresh report after DNS caches and platform changes have had time to update.