When you sign up for an email account at Google's Gmail, you have to navigate past a CAPTCHA--squiggly words and letters that need to be typed into a box to prove you're human and not an automated system looking to send spam. But in the war against spammers, CAPTCHAs are not holding up well and <A HREF="http://www.newsfactor.com/story.xhtml?story_id=131004IM4E0U">the latest attacks let spambots into Gmail.</A>

CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart." Typically image files, the challenge-and-response system has been fairly successful in preventing spammers from opening email accounts on popular Web domains like Gmail, Yahoo and Hotmail. Those accounts are prized by spammers because Web administrators can't simply blacklist the popular domains.