All Collections
Email Deliverability
What is TLS and how is it related to email?
What is TLS and how is it related to email?

TLS helps email in transit from being read by unauthorized parties. Read on to find out more.

Ivan Kovachev avatar
Written by Ivan Kovachev
Updated over a week ago

What is TLS in Email Communication?

TLS, when applied to email, is a protocol that encrypts and secures emails in transit between the sending and receiving servers. It's a key technology in preventing eavesdropping and tampering with email messages as they travel across the Internet.

How TLS Works in Email: A Simplified Example

  1. Initiating a Secure Connection: When an email server sends a message to another server, it can use TLS to establish a secure connection. The receiving server presents its TLS certificate, containing its public key verified by a Certificate Authority (CA).

  2. Encryption Handshake: The sending server verifies the certificate and then uses the public key to encrypt the email data. A unique encryption key is generated for this specific session.

  3. Secure Email Transmission: The email is transmitted over this encrypted connection / channel. Only the receiving server, with the corresponding private key, can decrypt and read the email. TLS doesn't encrypt the email, only the connection.

Who Sets Up TLS for Email?

TLS setup for email is usually handled by network administrators managing email servers. Email typically uses what is called Opportunistic TLS, which means that a client and server negotiate first before setting up TLS. If TLS negotiation fails, the emails are sent in the clear. You can however, configure your email server to always use TLS.

Benefits of TLS for Email Security and Reliability

  1. Email Encryption: TLS encrypts emails during transit, protecting sensitive information from being intercepted.

  2. Server Authentication: The use of TLS certificates ensures that emails are sent to and received from legitimate servers, reducing the risk of man-in-the-middle attacks.

  3. Data Integrity: TLS helps ensure that the content of the email remains unchanged during transit, maintaining its integrity.

  4. Enhanced Privacy and Compliance: TLS is crucial for privacy, as it prevents unauthorized access to email content. It also helps organizations comply with various data protection regulations.

  5. Building Trust: Using TLS signals to users that their email provider values security, which can enhance trust and credibility.

  6. Helps with setting up MTA-STS. TLS is a pre-requisite for MTA-STS.

In the context of email, TLS is vital for ensuring that messages are securely transmitted over the Internet, protecting the confidentiality and integrity of email communication. It's a fundamental part of modern email infrastructure, contributing significantly to the overall security of electronic correspondence.

Can I test my TLS configuration?

Yes, you can use our Investigate tool to test your email set up here. Alternatively, if you are already an OnDMARC customer, you can find the Investigate tool within your OnDMARC account, under Tools.

Did this answer your question?