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Run an instant test to verify your mail servers support STARTTLS, enforce modern TLS 1.2+ encryption, and use valid certificates. Protect your emails from transit interception.
STARTTLS is an email protocol command used in SMTP to upgrade a plaintext, insecure connection into a secure TLS/SSL encrypted connection. It ensures that emails are protected against snooping and modification while traversing the internet.
STARTTLS is typically "opportunistic." If the receiving server supports it, encryption is used. If not, the email is silently downgraded to plaintext to ensure delivery (unless MTA-STS policies are enforced).
Supporting STARTTLS isn't enough; you must support modern cryptographic protocols (TLS 1.2 or TLS 1.3). Older versions like TLS 1.0 are vulnerable to attacks like POODLE and BEAST.
Type your domain name into the lookup tool above.
We resolve your domain's mail exchange (MX) servers.
We simulate SMTP handshakes and issue the STARTTLS command.
We validate supported TLS protocols and TLS certificate chains.
Discovers all mail servers associated with your domain.
Checks if the server correctly advertises the STARTTLS SMTP extension.
Detects legacy encryption protocols (TLS 1.0, 1.1) and enforces TLS 1.2+.
Extracts certificate subjects, issuers, and expiration dates.
Identifies if attackers can easily force your connections into plaintext.
Provides actionable steps to upgrade your email encryption standards.