Glossary · DNS
TLS-RPT asks sending mail servers to report problems they hit establishing encrypted connections to your domain's mail servers.
Publish a TXT record at _smtp._tls.yourdomain with an address for reports (RFC 8460). Participating senders, including Google and Microsoft, send daily JSON summaries of successful and failed TLS sessions to your MX hosts.
It's most useful alongside MTA-STS: run the policy in testing mode, read the reports, and switch to enforce once they're clean.
_smtp._tls.acme.com TXT "v=TLSRPTv1; rua=mailto:tls-reports@acme.com"Every domain you run in one inbox, from $3 a mailbox. 14 days free, no card.