When a word is underlined in your email, it means there’s a Yahoo! Shortcut waiting to save you time. By hovering over the underlined word or phrase with your mouse, you’ll see a little menu of things to do—like adding someone’s info to your address book, getting a map of an address, adding an event to your calendar or searching for more info on a topic.
Yahoo! Mail underlines email addresses, phone numbers, locations, things of interest and calendar events. We're also working on other terms to turn into Yahoo! Shortcuts. They’re coming soon, so be on the lookout.