Transport security

What is MTA-STS?

How domains can ask sending mail systems to require a secure delivery path.

Secure mail transport

MTA-STS allows a receiving domain to publish which mail servers should receive its mail and require a valid TLS connection from supporting senders.

Visibility with TLS-RPT

TLS-RPT complements transport policy by reporting delivery failures related to TLS. Together they help surface where secure delivery could not be established.