MTA-STS Record Checker
MTA-STS tells sending mail servers to only deliver to your domain over TLS, blocking downgrade attacks. It needs a DNS record AND a policy file served over HTTPS.
Want ongoing monitoring?
This tool is a one-shot check. PhishFence watches your domain with automated hourly monitoring (daily on Free) for DMARC changes, new lookalike registrations, and spoofing attempts.