What Does Encrypted Email Mean: Definition and Methods

Encrypted email scrambles messages so only the right people read them. Think about sending a note in code. Nobody else deciphers it. We think this matters more now, with data leaks everywhere. Honestly, most folks ignore it until a breach hits. That’s why email encryption is more important than you think.

What is Email Encryption Meaning

Email encryption authenticates messages. It stops unauthorized eyes from reading them. The process scrambles the original text, turning it into something unreadable and confusing.

Sensitive data demands this protection when sent by email. Hackers love email channels. They target victims there, stealing names, addresses, login details. Then they commit identity theft or fraud.

Most emails encrypt during transmission only. Once stored, the content sits in plain text. Email providers can read it easily. Free services rarely offer end-to-end encryption, so intercepting messages becomes simple for attackers.

Solutions rely on public-key cryptography. They add digital signatures too. These tools encrypt messages fully, ensuring security. Only the intended recipient, holding the private key, can unlock and read the email.

How Encrypted Email Works

Public-key cryptography powers most setups. Two keys: public for locking, private for opening. Share the public one wide. Keep private hidden.

Sender grabs your public key, encrypts the message. You use private to read. Digital signatures add proof, like a seal. Can’t tamper without notice.

Symmetric keys sometimes mix in, faster for big files. But asymmetric rules for email. Keys generate via software. Exchange them securely first.

Policy-based systems automate. Scan

Email Encryption Types

Message-Level Encryption: Scrambles the content itself. Body, attachments, everything. Only the recipient unlocks it. Think S/MIME, PGP. This is the real private stuff. The servers can’t peek. It’s pure end-to-end;
Transport-Level Encryption: Secures the pipe between mail servers. TLS. Your email’s in an armored truck for the journey, but it’s plaintext at each stop. Standard now. Good for stopping network snoops, but not for server-side secrecy;
Client-Level Encryption: Your email app does the work. Outlook, Thunderbird with a plugin. It encrypts before the mail even leaves your machine. User-friendly. Gets messy if you switch clients. Brings strong crypto to normal people;
Gateway-Level Encryption: The company’s security box handles it. Everything going out gets encrypted automatically based on rules. An admin’s dream for control. But the gateway sees your plain email first. It’s about policy, not personal privacy;
Portal-Based Encryption: The email doesn’t get sent. A link does. “Click here for a secure message.” You log into a web portal to read it. Clunky. Bulletproof for compliance and audit trails. Works when the other side has zero tech setup. The necessary evil.

Email Encryption Methods

Now that we’ve covered, the encryption definition and what it is, let’s talk about how encryption works.

There are two main email encryption approaches. End-to-end encryption and transport-layer encryption.

Both PGP and S/MIME are end-to-end encryption methods.

This means the email is encrypted at its source (the sender), unreadable in transit (even to Gmail or other service providers) and then decrypted at the other end (the recipient).

On the other end, we have transport-layer encryption, which includes SSL, TLS and STARTTLS.

PGP

PGP includes two types of encryption, PGP/MIME and PGP Inline.

How does encryption work with these two?

PGP/MIME or Pretty Good Privacy Multipurpose Internet Mail Extensions (that’s a mouthful) is a decentralized encryption method that encrypts and signs the email message (along with any attachments) as a whole.

This type of encryption provides a good deal of control and flexibility over what gets encrypted. The issue is that since the entire message is encrypted together, you’ll need to download it whole (with attachments) in order to read the body.

PGP Inline, on the other hand, encrypts everything individually. In other words, the email body and any attachments will be separately encrypted and digitally signed.

There are advantages and disadvantages to this approach.

The biggest advantage is that the recipient doesn’t have to use a client that supports PGP. Instead, they can copy or download the message body or attachment and then use a 3rd party tool to decrypt it.

The problem, however, is that, since everything is encrypted separately, PGP Inline can leak information about the attachment.

S/MIME

Another email encryption method is S/MIME or Secure/Multipurpose Internet Mail Extensions. S/MIME is based on asymmetric cryptography and a pair of keys (public and private).

These two keys are mathematically related and one won’t work without the other.

That means you’ll need a public key to encrypt the message. However, you can only decrypt it with a private key, which only the intended recipient will have access to.

Since this encryption method is built into most OSX devices, it requires a centralized authority to pick the encryption algorithms, whereas PGP is more decentralized.

Transport-layer email encryption includes SSL, TLS and STARTTLS.

SSL and TLS

Both SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are application-layer protocols that allow the communication channel between two computers (sender and recipient) to be encrypted.

How does encryption work with SSL and TLS?

In essence, to send and receive emails, email client uses TCP or Transmission Control Protocol. This allows it to initiate a “handshake” with the server.

During the “handshake”, the email client informs the email server what version of SSL or TLS (they are interchangeable, the only difference is in the version you are using), what cipher suites and compression methods the server should use.

Once they’ve “shaken hands” the server will verify the client’s identity by sending it a certificate, telling the client that it is trusted by the user’s software (for example Microsoft).

This assures the email client that it is sending messages to who it should and not someone posing as the real recipient allowing the two to exchange the key with which all sent and received emails are encrypted.

STARTTLS

Since TLS and SSL are application layer protocols, this means that both the sender and the recipient have to know they are used to encrypt emails.

STARTTLS, on the other hand, tells the server that a client would like to make an insecure connection secure.

Best Practices for Encrypted Email

Choose strong tools. Providers like ProtonMail or Tutanota build encryption directly into their systems. Messages stay protected from start to finish.

Always verify recipient keys before sending sensitive files. A mismatched key means the wrong person could access everything, and recovery becomes impossible without backups.

Train yourself to enable encryption manually when needed. Many clients hide the option deep in menus, so practice often. Short habits prevent big leaks.

Combine encryption with secure passwords and two-factor authentication. Weak logins undo all protection. Attackers shift targets quickly once they spot easy entry points.

Delete sent messages after confirmation of receipt, especially on shared devices. Storage habits matter. Old copies linger in unexpected folders. Clear them regularly to reduce risks over time.

Why is Email Encryption Such a Big Deal

So why are we telling you all of this about email encryption? Why is it important to know how encryption works, to understand the different encryption methods and so on?

Millions of dollars are lost every year due to unsecured email communication. Email breaches can have a significant negative impact on your organization. This includes not only financial loss, but reputation loss as well.

For instance, this year over 2 billion customer personal records from an email marketing service Verifications.io were exposed in what is likely the largest email data leak in history.

Verifications.io is one of the largest email verification platforms out there and if anyone should know how to keep emails secure, it’s them. However, they were still a victim of a data breach which exposed their customers’ personal information, which hackers and scammers could then use for illegal purposes, like identity theft.

If email data leaks can happen to companies like Verifications.io, it can happen to you as well, so it’s better not to risk it and make sure your emails are properly encrypted.