from bloomberg.com: Yahoo! Inc. (YHOO), the biggest U.S. Web portal, said it recently identified an effort to break into some users’ Yahoo Mail e-mail accounts. The list of names and passwords used in the attack was probably taken from a third-party database, Yahoo said yesterday in a blog post. The company said it acted immediately to protect users by prompting holders of affected accounts to reset their passwords and that it’s working with federal law enforcement agencies to find out who was responsible. The breach follows other issues in the past year with Yahoo Mail, which has more than 100 million daily users. Chief Executive Officer Marissa Mayer has been criticized by some customers for changes she’s made to the organization and design of the service, and Mayer apologized in December for “compounding issues,” including lost messages, users being shut out and trouble with access to other e-mail programs.