What Is TLS And How Does It Help Protect My Emails?

What Is TLS And How Does It Help Protect My Emails?

Transport Layer Security (TLS) is a protocol that helps protect emails by encrypting the communication channel between sending and receiving mail servers. Encryption in transit makes it significantly harder for third parties to intercept or read email messages while they are being delivered.

Encrypting email traffic is important to reduce the risk of eavesdropping as messages travel across the internet.

When two mail servers communicate, they attempt to negotiate a secure TLS connection. If both servers support TLS, the email is transmitted over an encrypted channel.

If TLS negotiation fails or is not supported, one of the following may occur:

  • The sending server may deliver the email without encryption (in clear text), depending on its configuration.

  • Alternatively, the sending server may refuse to deliver the email if encryption is required.

TLS protects email in transit only and does not encrypt messages stored on mail servers or in recipients’ mailboxes.


For domains that require TLS encryption and do not allow unencrypted fallback, MTA-STS can be implemented to enforce secure email delivery.

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