Ever pass by a co-worker's unattended computer and consider taking a peek at her e-mails? Or have you ever thought it would be a funny prank to figure out your cube mate's e-mail password and break into his work account to mess with him?

What may seem like a practical joke or a harmless, furtive glance actually could land you in more hot water than you'd ever expect. It could go as far as getting you fired or even charged with a federal crime.

The recent case of a Philadelphia TV news anchor charged with breaking into his co-anchor's e-mail accounts shines a light on the seriousness of such snooping. And while Lawrence Mendte, the news anchor at CBS affiliate KYW-TV, took his e-mail snooping to an extreme, security analysts and lawyers say seemingly simple actions can quickly turn into criminal matters.

And the problem is that people often don't realize that breaking into or surreptitiously eyeing a colleague's e-mail actually is a crime.

"I don't think people are of the understanding that this type of conduct is a crime," said Scott Christie, a former federal prosecutor who headed up the computer hacking and intellectual property section at the U.S. Attorney's Office in New Jersey. "You look over someone's shoulder and read a personal letter and that's not a crime, so how can it be a crime to access someone's e-mail? It's not the same thing, of course. Part of the lack of understanding comes from the fact that e-mail is so common these days and people whip them off without thinking twice.

"What you're dong when you're accessing e-mail is affirmatively exceeding your access to electronic documents and systems," he added. "Usually, you're doing that by pretending to be that person to break into their account."

Snooping into other people's e-mail messages, no matter if it's meant as a prank or is but a one-time thing, is in most circumstances a crime.

Ken van Wyk, a consultant at KRvW Associates, said he suspects that taking a surreptitious look at co-workers' e-mail is a common occurrence in business. "For a co-worker to snoop, that would take some work, but for a sys admin to do it, that's trivial," he added. "That's where abuses are more likely. If someone was caught doing it, I'd generally expect a pretty ugly situation."

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