What does it mean when an email is encrypted?

Email encryption involves encrypting, or disguising, the content of email messages in order to protect potentially sensitive information from being read by anyone other than intended recipients. Email encryption often includes authentication.
As PC world points out, it’s not just those who may email sensitive information, such as Social Security numbers, login credentials, or bank account numbers, who need to encrypt their email. Hackers who gain unauthorized access to an email account can access attachments, content, and even hijack your entire email account.
Email is a vulnerable medium, particularly when emails are sent over unsecured, or public, Wi-Fi networks. Even emails sent within a secure company network can be intercepted by other users, including your login credentials. Encryption renders the content of your emails unreadable as they travel from origin to destination, so even if someone intercepts your messages, they can’t interpret the content.

EMAIL ENCRYPTION: WHAT TO ENCRYPT

PC World points out three primary things you should encrypt:

The connection from your email provider
Your actual email messages
Your stored, cached, or archived email messages
Encrypting the connection prevents unauthorized users on the network from intercepting and capturing your login credentials and any email messages you send or receive as they leave your email provider’s server and travel from server to server around the Internet.

Encrypting email messages before they’re sent means that even if a hacker or anyone other than the intended recipient should intercept your email messages, they’re unreadable, and essentially useless.

Finally, if you store backed-up email messages in an email client, such as Microsoft Outlook, hackers may gain access despite password protection of your accounts and even your device. Email encryption ensures that even if access is obtained, the content of your email messages is unreadable.