Pro move: type dmarc:yourdomain.com or blacklist:1.2.3.4 straight into the box — it switches tools for you.
About this tool. TLS-RPT is the companion to MTA-STS: it asks providers to send you a daily report whenever encrypted delivery to your domain fails. One DNS record, and you'll actually know when something breaks.
How to read your tls-rpt checker results
TLS-RPT publishes an address where other servers send reports when TLS delivery to you fails. It is how you find out about encryption problems.
It is a simple TXT record at _smtp._tls.yourdomain with a reporting destination.
Common problems and how to fix them
You enforce MTA-STS but see no reports
Add a TLS-RPT record so failures are reported. Without it, downgrade or certificate problems stay invisible.
Common questions.What is TLS-RPT?
SMTP TLS Reporting. It asks sending servers to report failures in encrypting mail to you, so you can catch problems early.
Do I need MTA-STS to use TLS-RPT?
They pair well but are independent. TLS-RPT gives you visibility; MTA-STS enforces the encryption.