Enforce TLS email encryption and prevent SMTP man-in-the-middle downgrade attacks (STARTTLS).
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. Zero egress.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
Provide your domain name and authorized mail server patterns.
Choose enforce, testing, or none.
Download mta-sts.txt and copy the _mta-sts TXT record.
It must be hosted at https://mta-sts.yourdomain.com/.well-known/mta-sts.txt over HTTPS with a valid certificate.
Enforce mode instructs sending mail servers to refuse delivery if TLS is absent, while testing mode delivers mail and reports failures via TLS-RPT.
Zero-egress companion tools in the Security & Network suite
Measure cryptographic randomness, Shannon entropy (0-8 bits/byte), Chi-square test, and byte distributions.
Brute-force all 256 single-byte XOR keys with automated English frequency & chi-squared scoring.
Audit CSP, HSTS, X-Frame-Options, and security headers with OWASP grading (A+ to F).
Compare memory hardness, GPU ASIC resistance, and security parameters across KDF standards.
