To encrypt the transmission of e-mail from our e-mail clients (Outlook, Thunderbird, Windows Mail, iMail, iPhone Mail, Android Mail, etc.) to our e-mail servers, many of us (whether we know it or not) are using STARTTLS.
STARTTLS is a way for clear text communication protocols to “upgrade” to a secured connection. If client and server both support encryption, they establish an encrypted connection and communicate over it. If either the client or the server does not support encryption, they will fall back to an unencrypted connection and communicate in clear text.
Here is an article on how a certain internet service provider was caught tampering with this process to prevent secured e-mail connections from being established:
If you run an e-mail server, now may be a good time to change the settings to where encryption is non-negotiable and required for SMTP client submissions…