My LR 4.4 isn't allowing me to send emails of pix, do they want a password for yahoo or Lightroom Account Manager?
Most likely LR wants your email username and email password so that it can talk directly to the email server.
Yahoo complicates this process in an attempt to trick users into thinking they have improved security since their last hacking.
To work with Yahoo mail servers, you need to use a web browser to go to your Yahoo account. In the security settings you need to create a special password for LR to use as a third party email program.