During the 2008 presidential election, the internet became a giant rumor mill. For example, there were the viral e-mails claiming that Barack Obama's birth certificate was a fake. Or ones spreading the phony Sarah Palin quote, "God made dinosaurs 4,000 years ago". Some political scholars worry the Web could undermine democracy, by misinforming and polarizing voters. But Web sites and blogs don't serve up the most influential rumors. Our in-boxes do. So says a study of e-mail in the journal Human Communication Research. Just after the election, researcher R. Kelly Garrett randomly surveyed 600 Americans about their online habits, and whether they'd heard—and believed—a number of widespread rumors. He found that the Web does expose us to more rumors. But the Web also delivers more rebuttals, which can even the field. E-mail's more insidious. Because you're more likely to believe that rumor forwarded by cousin Rob. And the more you believe something, Garrett says, the more you want to share it with your social network—spawning a nasty cascade of misperception. So before you hit SEND to forward e-mail, ask yourself: Do I know the item I'm sharing is true, or do I just want it to be?