Email currently uses an HTTP request to https://mta-sts.<domain>/.well-known/mta-sts.txt, per RFC 8461. Depending on HTTPS/TLS instead of DNSSEC is one major reason you see this approach gaining popularity.
Email currently uses an HTTP request to https://mta-sts.<domain>/.well-known/mta-sts.txt, per RFC 8461. Depending on HTTPS/TLS instead of DNSSEC is one major reason you see this approach gaining popularity.