While you are reading a Mail message from a friend who is also a Yahoo! Mail user, you will see a Call link in the top right corner of the page above the reply buttons. Simply click this link and Yahoo! Messenger with Voice will confirm your action and then begin placing the call to your friend. – It's that easy!

If your friend isn't a Yahoo! Mail or Yahoo! Messenger with Voice user, invite them to sign up so that the two of you can talk, and talk, and talk, and talk.