What is TLS?
TLS stands for Transport Layer Security. It is a security protocol designed to help encrypt communication between systems connected over a network.
In email environments, TLS can protect connections between user devices and mail servers as well as communication between separate mail servers.
Protecting data during transmission
When TLS is active, message data travels through an encrypted connection rather than being transmitted as plain network traffic. This reduces the risk of information being intercepted in transit.
STARTTLS with SMTP
Mail servers can begin an SMTP connection and then upgrade it to an encrypted session using STARTTLS. Support for modern TLS by both servers is important for secure transport.
TLS for IMAP connections
TLS is also commonly used when users access their mailboxes with IMAP. Secure IMAP connections generally use port 993.
TLS does not prevent every threat
TLS protects the communication channel but does not eliminate phishing, malicious attachments or compromised accounts. Secure business email also requires strong authentication, spam protection and sender validation.
Modern business email infrastructure
Organizations should make sure their email platform supports current TLS versions and uses valid digital certificates for protected communication.