What Is TLS and STARTTLS in Email Encryption?

Every time an email travels between servers, it can either go in the clear or be encrypted. TLS and STARTTLS are what make that encryption happen. Here's a plain-English explanation.

TLS in one line

TLS (Transport Layer Security) is the same encryption technology that protects websites (the padlock in your browser). For email, it encrypts the connection between mail servers - and between your device and your mailbox - so the contents can't be read in transit. It's the "encryption in transit" half of email encryption explained.

Where STARTTLS fits in

STARTTLS isn't a different kind of encryption - it's a command that upgrades a plain connection to an encrypted one. A sending server connects, issues STARTTLS, and the two servers switch to a secure TLS channel before any mail is exchanged. Many email connections start this way.

You'll also see implicit TLS, where the connection is encrypted from the very first moment on a dedicated secure port. Both achieve the same result: an encrypted channel.

Why it matters for business

• Privacy - mail isn't readable by anyone intercepting the connection
• Integrity - contents can't be quietly tampered with in transit
• Trust and compliance - encrypted transport is a baseline expectation, see email compliance for business

What TLS does and doesn't cover

TLS protects email while it moves. It doesn't, by itself, prove who sent a message or stop spoofing - that's the job of authentication. Pair transport encryption with SPF, DKIM and DMARC for the full picture. See SPF, DKIM and DMARC explained. For protecting stored mail, see encryption at rest in email encryption explained.

Encrypted by default

You shouldn't have to think about TLS - it should just be on. DigiCloudMail enforces modern TLS on connections and encrypts mail at rest, so your business email stays private end to end of its journey.

Want email that's private by default? Contact us.