Loggin into Drupal using Yahoo mail
Try the RPX (Janrain Engage) module.


  Using Janrain Engage, Drupal sites can authenticate new and existing
  users with popular social networks, map user profile data from these
  websites to Drupal fields, and share Drupal content with a user's
  friends on their social networks.
  
  This includes Facebook, Twitter, Google, Yahoo!, LinkedIn, Myspace,
  AOL, PayPal, and Windows Live (see the complete list below).