Check out the OIPA: Openaid IATI API.
Service Security Monitoring and Validation
Multiple in-depth checks related to TLS configuration, certificates and other aspects of domain security configuration. The API can perform MTA-STS (RFC-8461) and SMTP TLS Reporting (RFC-8460) configuration validation. Checks use DNSSEC-validating resolvers and include these results in the diagnostics exposed in the results.
Connect to API