What is STARTTLS?

What is STARTTLS?

STARTTLS is a command used to upgrade an existing, plaintext connection to a secure, encrypted connection using SSL/TLS. Unlike connections that begin encrypted (such as those on port 465 for SMTP), STARTTLS starts as a plaintext connection and then transitions to encryption. This approach is commonly used in email protocols like SMTP, IMAP, and POP3.

How STARTTLS Works

1. Initial Connection: A client connects to the server on a port that supports plaintext communication (e.g., port 587 for SMTP).
2. STARTTLS Command: The client issues the STARTTLS command to the server.
3. Upgrade to TLS: The server responds positively to the STARTTLS command, and both the client and the server upgrade the connection to use TLS encryption.
4. Encrypted Communication: Subsequent communication on this connection is encrypted using TLS.

Benefits of STARTTLS

• Security: STARTTLS provides a way to secure communications without requiring a separate port for encrypted traffic.
• Compatibility: Since it starts as a plaintext connection, it can be used with servers and clients that do not initially support encryption.
• Flexibility: It allows for a single port to support both encrypted and non-encrypted communications, simplifying firewall configurations and server setup.

STARTTLS in Nodemailer

When configuring Nodemailer, using STARTTLS involves setting secure to false and connecting to a port that supports STARTTLS (typically port 587)..