What is Encryption and Why Does It Matter for Your Emails

I spend a lot of my time thinking about digital privacy. I'm not trying to hide anything dodgy, but I do think our private conversations, whether they're in our living rooms or in our inboxes, should stay that way. For years, email's been one of our go-to ways of chatting, but most of us don't really know how easily it can be hacked.

Just imagine sending every piece of mail on a postcard. Anyone who handles it along its route—like a postal worker, someone at the sorting facility, or even your nosy neighbour—can read its contents. That's basically what happens when you send an unencrypted email. The answer to this digital postcard problem is email encryption.

When you hear the word "encryption", you might think of spies and top secret government codes, but actually it's a pretty simple idea that's really important for keeping things secure these days. In this post, I'm going to break down encryption for you, explain how it works in the context of your email, and convince you why you should care deeply about it.

So, here's the deal: you can use this for business and personal use.

The Core Idea: Turning Language into a Secret Code

At its heart, encryption is the process of taking readable information (known as plaintext) and scrambling it into an unreadable format (ciphertext) using a secret "key." Only someone with the correct key can unscramble the ciphertext back into its original, readable form.

Think of it like a locked box. You put your message inside, lock the box with a unique key, and send it on its way. If anyone intercepts the box, it's useless to them without the key. They can't see what's inside. Only the intended recipient, who has a copy of the key, can unlock it and read your message. This fundamental principle is what makes email encryption possible.

The Two Main Flavors of Encryption: A Simple Breakdown

In the digital world, those "keys" are sophisticated cryptographic algorithms. There are two primary types of encryption that you'll encounter, and understanding the difference is key to grasping how your email is protected.

1. Symmetric Encryption: This is the simpler of the two. It uses a single, secret key to both lock (encrypt) and unlock (decrypt) the information. Both the sender and the receiver must have the exact same key. It's fast and efficient, but its main challenge is key distribution. How do you securely share the secret key with the recipient in the first place without someone else intercepting it?

2. Asymmetric Encryption (Public-Key Cryptography): This is where things get really clever and form the backbone of modern email encryption. Asymmetric encryption uses a pair of keys for each person: a public key and a private key.

The public key can be shared with anyone. Think of it as the address and open slot of your personal, secure mailbox. Anyone can use your public key to encrypt a message and send it to you.

The private key is kept completely secret by you and you alone. It is the only key that can decrypt messages that were encrypted with your corresponding public key.

So, if I want to send you a secure message, I find your public key (which you can freely list anywhere), use it to encrypt my email, and send it to you. The message is now scrambled. Even if it's intercepted, no one can read it. When you receive it, you use your secret private key to decrypt it back into readable text. This process elegantly solves the key-sharing problem of symmetric encryption.

Where Encryption Happens: The Journey of Your Email

Email encryption isn't just a single on/off switch. It can be applied at different stages of an email's journey from your "Send" button to your recipient's inbox.

Level 1: Encryption in Transit (TLS)

The most common and basic form of email encryption is called Transport Layer Security (TLS). Its job is to protect your email as it travels from your computer to your email provider's server, and then from your provider's server to the recipient's provider's server. It creates a secure, encrypted "tunnel" for the email to travel through.

You see TLS in action every day when you visit a secure website with "https://" in the address bar – that "s" stands for secure. Most of the big email providers (like Gmail, Outlook, etc.) use TLS these days. This is great because it stops hackers snooping on your Wi-Fi at a coffee shop from reading your emails as they travel over the network.

The Weak Link: The problem with relying solely on TLS is that the protection is not continuous. The email is encrypted while it's in the tunnel, but when it arrives at a server (like your provider's), it is often decrypted and stored. This means the email provider itself can access the content of your emails. They do this for various reasons, including scanning for spam and targeting ads. If that provider gets hacked, your plaintext emails are vulnerable. For a deeper technical dive into how TLS handshakes work, the Internet Engineering Task Force's (IETF) RFCs are the authoritative source.

Level 2: Encryption at Rest

This refers to the encryption of your emails while they are being stored on a server. When your emails are sitting in your inbox, they are "at rest." Most providers do encrypt your data at rest, which is a crucial security measure. It means if a thief were to physically steal a hard drive from one of their data centers, they wouldn't be able to read the stored emails without the provider's encryption keys.

The Weak Link: The provider still holds the keys. This means they can decrypt the emails themselves to comply with government requests or for their own data analysis. So while it protects against physical theft, it doesn't protect your privacy from the provider itself.

The Gold Standard: End-to-End Email Encryption (E2EE)

This brings us to the ultimate goal for truly private communication: End-to-End Encryption, or E2EE.

As the name suggests, E2EE ensures that a message is encrypted on the sender's device and can only be decrypted by the intended recipient's device. No one in between—not your internet provider, not your email provider, not even a government agency that legally requests it—can read the message.

This is where the asymmetric (public/private key) system truly shines. When you use an E2EE email service:

-Your email is encrypted on your computer/phone using the recipient's public key before you hit "Send."

-The scrambled, unreadable ciphertext travels across the internet.

-Your email provider stores this unreadable ciphertext. They have no way to decrypt it because they don't have the recipient's private key.

-The recipient receives the ciphertext and their email client uses their secret private key to decrypt the message locally on their own device.

This is the only method that guarantees that you and your recipient are the only two people who can read the email. It completely removes the email provider from the "circle of trust."

Why This Actually Matters For Your Emails

At this point, you might be thinking, "This is interesting, but I'm not a spy. Why do I need this level of email encryption?" The reasons are more practical than you might think.

Identity Theft and Financial Fraud: Your email inbox is a treasure trove of sensitive data: bank statements, password reset links, tax documents, investment details, and online shopping receipts. Leaving this unencrypted or poorly encrypted is like leaving your wallet on a park bench. A breach could give a criminal everything they need.

Business and Professional Confidentiality: If you're a lawyer, doctor, therapist, or business owner, you have an ethical and often legal obligation to protect client confidentiality. Sending sensitive client information over a non-E2EE service is a massive liability.

Personal Privacy and Autonomy: Your private conversations should remain private. Who you talk to, what you say, and what you share is nobody else's business. In an age of rampant data collection, using email encryption is a powerful way to reclaim your digital autonomy and draw a line in the sand.

Protection from Mass Surveillance: While you may trust your own government, your emails travel across servers all over the world. Using E2EE protects your communications from being swept up in broad surveillance programs from various global actors.

Ultimately, the argument for encrypted mail is the same as the argument for having curtains on your windows. It's not about hiding illegal activities; it's about maintaining the boundary between your private life and the public world.

You don't need to be a technical genius to start using strong email encryption. Services are emerging that have built E2EE into their core product, making it seamless and user-friendly. The most important step is recognizing its importance and deciding that your digital conversations are worth protecting. The postcard era of the internet is over; it's time we all started sending letters in securely locked boxes.