MailTester Ninja

← all free tools

MTA-STS Checker

MTA-STS lets a domain require that incoming mail be delivered over TLS, defeating downgrade attacks. TLS-RPT asks senders to report TLS failures. This checker verifies both DNS records are published.

MTA-STS Checker, FAQ

What is MTA-STS?
MTA-STS (SMTP MTA Strict Transport Security) is a standard that lets a domain declare, via a DNS record and an HTTPS-hosted policy, that senders must use TLS to reach its mail servers.
What is TLS-RPT?
TLS-RPT (SMTP TLS Reporting) is a DNS record at _smtp._tls asking sending servers to send you reports about TLS connection failures, so you can spot delivery or interception problems.
Do I need MTA-STS?
It is optional but recommended for any domain that handles sensitive mail, it prevents attackers from stripping encryption between mail servers.

Want the complete picture? The Deliverability Radar scores a domain or IP out of 100 across DNS, authentication, reputation and connectivity, and emails you a branded PDF.

More free tools: SPF Checker · DMARC Checker · DKIM Checker · MX Lookup · Reverse DNS Lookup · Blocklist Checker · DNS Lookup · Blocklist Checker

Data · Email checker · Email verifier · Blocklist checker · Blocklists explained · Widget
Built & updated automatically by MailTester Ninja, the email verifier that stores nothing. DNS-only, aggregate data, no personal information. · JSON API · RSS