5. Yahoo Acquired Four11; Birth of World’s Most Popular Email

Yahoo is infamous for the dumbest acquisitions it made but this buy was an exceptional case among them. Yahoo acquired Four11, including RocketMail, one of the first free web based mail services in 1997 for $97 million. Yahoo incorporated the RocketMail engine into its service and made the world’s popular Email service, Yahoo Mail, which is still the most important product for the struggling company