STARTTLS Studio is part of DNS Studio, a suite of focused, free tools for checking DNS, mail authentication, TLS, SSL and domain trust. Each tool does one job clearly, in plain language, with a Tech mode when you want the raw detail.
How it works
For each of a domain’s MX hosts, we connect over SMTP, check that STARTTLS is offered, complete the TLS handshake, and read the certificate: who issued it, whether it is currently valid, whether it matches the mail host, and which TLS version and protocols were negotiated.
Private by design
There are no accounts and no advertising trackers. The domain you check is used only to perform the lookup and show you the result. See our Privacy page for details.
The rest of the studio
Looking for something else? Try DNS Studio for records and propagation, DKIM, DMARC and BIMI for mail, or TLS and SSL for certificates. The full list is in the footer.
Contact
Feedback and corrections are welcome at [email protected].