How to Secure SMTP Email Delivery with TLS
Tuesday, August 29th, 2023Secure email sending is a priority for organizations that communicate sensitive data externally. One of the most common ways to send secure emails is with SMTP TLS. TLS stands for Transport Layer Security and is the successor of SSL (Secure Socket Layer). TLS is one of the standard ways that computers on the internet transmit information over an encrypted channel. In general, when one computer connects to another computer and uses TLS, the following happens:
- Computer A connects to Computer B (no security)
- Computer B says “Hello” (no security)
- Computer A says, “Let’s talk securely over TLS” (no security)
- Computers A and B agree on how to do this (secure)
- The rest of the conversation is encrypted (secure)
In particular:
- The conversation is encrypted
- Computer A can verify the identity of Computer B (by examining its SSL certificate, which is required for this dialog)
- The conversation cannot be eavesdropped upon (without Computer A knowing)
- A third party cannot modify the conversation
- Third parties cannot inject other information into the conversation.
TLS and SSL help make the internet a more secure place. One popular way to use TLS is to secure SMTP to protect the transmission of email messages between servers.
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SMTP TLS (Transport Layer Security) is the mechanism by which two email servers, when communicating, can automatically negotiate an encrypted channel between them so that the emails transmitted are secured from eavesdroppers.
