Go ahead, email your credit card number to the person who needs it. Send your buddy the secret formula to Classic Coke. Email confidential information anywhere, ensuring the only people reading your email are those you intended to see it.

This is possible thanks to email encryption.

Normally, all email is sent in a way easily intercepted and read by those with some basic knowledge. "Public key" and "private key" email encryption techniques enable users to hide the contents of any email message, protecting the information with complex, unbreakable mathematical formulas.

How to encrypt email?

There are many email encryption services and software. The amount of effort encryption requires is determined by how much effort you want to do yourself, versus using a service to handle the workload. For example, you can manually encrypt and decrypt email every time you send and receive a message. Not terribly difficult, but it does take a few extra clicks, and adds an extra layer of complexity. Or use a remote service to do all the work for you. The downside is you must trust the service completely if they'll be managing your private, super-secret email.

Hushmail gives you free encrypted email immediately, with no hassle and very little confusion. Their web-based interface lets you send encrypted email to anyone, even those without encryption programs of their own. Use the service at least once every three weeks to keep your free account active. Purchase a paid account to get additional functions, like extra storage space, or a Microsoft Outlook plug-in (this allows you to get Hushmail's encryption functionality from within the Outlook email client). Hushmail use is simple and fast.

pGeep is free encryption software package. It has two parts. There's a standalone piece, allowing you to encrypt and decrypt email, text and files as needed. There's also a plug-in for most major email clients (like Outlook, Outlook Express, Thunderbird, Netscape and others). This allows you to have encryption functionality built right in to your email program of choice. Though you have to do more manual work to encrypt and decrypt, the upside is you don't have to trust a third-party to handle your sensitive information. This do-it-yourself encryption is fairly easy and fast.

PGP Desktop Home edition is for when you really mean business. Spend $100 for the ultimate in home user full system encryption. Yes, PGP Desktop will encrypt your email, but also instant messages (like those sent with AOL Instant Messenger) and every file on your PC. PGP Desktop is designed to scale to user's experience level. Set up your encryption preferences once, and forget about them. Or if you're a techie, configure PGP to a very detailed level. You set the complexity.

These techniques will protect you from electronic eavesdroppers and email sniffing software. They will not protect you from the "person reading over your shoulder" technique. If that's your problem, I recommend a low-tech, moderate cost, but very effective solution: A sombrero.