Spam emails not only drive you crazy, they contribute to global warming.

RODALE NEWS, EMMAUS, PA—Spam isn’t just rubbish e-mail that clogs your in-box with porn ads, scams, and promises of free shipping. This online annoyance has a dirty secret: It creates 17 million metric tons of greenhouse gases a year, which is equivalent to the emissions from about 1.5 million U.S. homes, according to a new report. Beyond that, these pesky e-mails are also cluttering our minds and wrecking our sleep.

THE DETAILS: Security technology company McAfee commissioned ICF International (which has been looking at carbon footprint issues for more than 20 years) to investigate the environmental impact of spam (the electronic kind, not the canned meat). ICF tracked spam in 11 countries and found that the energy required each year to create, send, receive, store, and view junk e-mail adds up to more than 33 billion KWh, about the same amount of power created in a year by four new coal-fired power plants. Nearly 80 percent of spam’s greenhouse gas emissions comes from the energy expended while you have to waste time online viewing and deleting spam, sifting through junk e-mail to find legitimate messages.

Besides adding greenhouse gases to the atmosphere, spam e-mails also add stress to your day, says Jeffrey Rossman, Ph.D., director of life management at Canyon Ranch in Lenox, MA, and Rodale.com advisor. “Spam does cause stress, as people have to sort through it to get to their truly important messages. It not only takes precious time, it requires making decisions as to whether to open it or not, and if you do, what to do with it,” he explains. “Many people find that information overload is a huge source of stress, which when combined with our cultural tendency toward multitasking, leaves us in a state of continuous partial attention. It's like a culturally induced ADD.”

WHAT IT MEANS: It’s obvious that receiving four Victoria Secret catalogs a week through snail mail has environmental costs in terms of producing, shipping, and disposing of all that paper. But now we know that unwanted electronic junk mail produces a negative impact, too. We spend so much time trying to figure out what’s legit in our in-box that we wind up burning more energy and stressing ourselves out in the process.

Here’s how to save some energy—and sanity—by toning down your electronic junk mail emissions.