All tools
TLS & SSL
MTA-STS Checker
Fetch and validate the MTA-STS policy for any domain. Check mode (testing/enforce), MX matching, and max_age.
This tool is being wired up. The analyzer ships in the next build phase.
About this check
Fetch and validate MTA-STS policy files.
Frequently asked questions
- What does the MTA-STS Checker actually check?
- Fetch and validate MTA-STS policy files.
- Is this really free?
- Yes. Every on.bo tool is free, no signup required, no rate-limit tricks.
- Do you store the data I check?
- We log minimal metadata to keep the service healthy. Lookups themselves are not retained beyond short-term caching.