You can never be sure an e-mail message is private, but in an effort to up the security ante, some people encrypt their more sensitive e-mails.
Marcus Hodges, who works in the computer security field, guesses he encrypts about 5 percent of his e-mails.
"Anytime I am sending something that I care about that identifies me as a person, or I don't want other people reading — absolutely, I do it," he says.
Hodges and his computer security colleagues wonder why more people don't take such precautions.
Encryption doesn't require an obscure hacker's tool. There are lots of encryption programs available, many for free. Most of them are versions of something called "public key encryption."
Phil Zimmermann is one of the godfathers of e-mail encryption — he even rates a passing mention in The Da Vinci Code, the popular novel by Dan Brown. In the early 1990s, Zimmerman released something called "PGP," short for Pretty Good Privacy, an encryption software for the masses.
Here's how it works: You download the software, then write someone who has encryption software an e-mail using his or her public key — which the person can give to anyone. When the person receives the e-mail, he or she decrypts it by using a private key.
"It's like having two keys to your front door. One of them unlocks the door, the other one locks the door," Zimmerman says.
Some experts say encryption hasn't caught on because there isn't a single standard. Others blame Microsoft for having made its Outlook encryption system so hard to figure out.
Some people, such as Angela Pettino, just don't care.
"I mean it's weird thinking that somebody can look at your private stuff, but it doesn't really bother me that much," Pettino says while using her laptop in an Internet café in Seattle.
Another Internet surfer takes it a step further: Kevin Drexel says he tries to live a life fit for public scrutiny — and that includes e-mails.
"I've kind of made being a public person just a personal policy. It's just a rule for living," he says. "Just live in a way in which you wouldn't mind that it was all public information."