The time you spend at work surfing online or shooting off emails to friends and colleagues may feel like an island of private time in the public sea of your workday, but don't trust that feeling.

More than ever, employers are monitoring email messages and Internet use, and a fair number say they've disciplined workers for abusing their electronic privileges, according to two recent surveys.

Seventy-six percent of firms monitor which Web sites their workers visit, up from 62% in 2001, and 55% review employees' email messages, up from about 47% in 2001, according to the latest Electronic Monitoring & Surveillance Survey from the American Management Association and The ePolicy Institute.

The message to workers? "When you sit down at your office computer, you have no reasonable expectation of privacy," said Nancy Flynn, executive director of The ePolicy Institute and author of "email Rules."

"Federal law here in the U.S. clearly states that the computer system is the property of the employer and as such the employer has the right to monitor all email activity and Internet activity," she said.

"If your email is being monitored and if you send a message that violates your company's policy and you end up terminated for that message, you'd have a real hard time making a claim of invasion of privacy stick," Flynn said.

Companies that use email monitoring software set up that tool to alert them on a variety of subjects, Flynn said.

"It can be sexually explicit language. It can be the names of competitors if an employer wants to know who's looking for a job or who's maybe selling trade secrets," she said.

"It can be the names of the company's own executives if the organization wants to be certain they don't have employees who are transmitting embarrassing documents to outside parties," she said. "It's really across the board, what employers are looking for."

In some cases workers are well aware companies are monitoring their Internet use: 65% of firms block access to some Web sites, up from 38% in the 2001 survey.

And most companies -- though not all -- tell their workers about their monitoring of computer time: 89% let employees know their Web use is being tracked, and 86% tell workers their email is being monitored.

Percentage fired stays flat

The good news for workers: Firings over email infractions did not increase. Twenty-five percent of firms said they fired a worker over misuse of email, the same portion as did so in 2004. But that is up from about 21% in 2001.

While the survey didn't ask companies about email related terminations, Flynn speculated that firings over email messages may start declining as more companies educate workers about their policies and as more companies institute strict compliance policies.

"It's possible that as companies continue to put written policies into place and engage in formal policy training and have a compliance officer on site to help ensure compliance, that maybe we will see a decrease in the number of employees whose violations are so severe that the companies feel they need to terminate," Flynn said.

The AMA, an industry trade group, and the ePolicy Institute, a training and consulting firm, surveyed 526 companies. Firms were contacted via emails sent to the two groups' member lists, and to email lists of two software vendors and another trade association.

Fired over illicit images

A separate, smaller telephone survey of 50 companies in the Fortune 500 found that 50%, or 25 firms, had disciplined workers for abusing company policies regarding pornographic images in the workplace.

Of those 25 companies, 44%, or 11 firms, had fired a worker over the pornographic images.

Whether a worker sends pornographic pictures by email, or simply views such images on a computer screen visible to other workers, that can play a part in a sexual-harassment lawsuit.

"What's at stake for the company is a sexual-harassment [or] hostile work environment" lawsuit, said Jack Mangan, vice president of business development for PixAlert, a Dublin, Ireland and Boston-based maker of software for firms to monitor illicit images.

PixAlert commissioned Atlanta-based Delta Consulting, a market research firm, to conduct the survey.

"Even if it doesn't go as far [as a lawsuit], there are productivity issues with employees who are maybe spending too much time looking" at the images, Mangan said.

What's that you say?

Telephone use is another area firms are monitoring, according to the ePolicy Institute survey.

Fifty-one percent of firms, up from 9% in 2001, said they track the amount of time workers spend talking on the phone and the numbers they call, that survey found.

And companies are jumping to manage newer technologies as well, with 27% putting policies in place to address workers' personal cell phone use and 19% with policies laying out the appropriate use of camera phones in the workplace.

"In the first case, it's an issue of productivity and in the second case, you don't want employees transmitting via their camera phones objectionable content that could offend somebody and result in a harassment lawsuit," Flynn said.

Six percent of firms said they'd fired workers for misusing office phones, and 22% disciplined workers for doing so.