You have to use the user name and password in the account you specify in the account properties in the email program (like Windows Live Mail or Thunderbrid).
But you can do that in different Windows- accounts on the same PC, or on different device (like a PC, laptop, tablet).
Be sure that if you use pop3 e-mail you set it to leave the mail on the server for some time in all e-mail programs, otherwise only the first will be able to download it and it's gone for the others.
I have a yahoo as well AOL email Account. I want that one of my family will use same account but with different user and password .
Is It possible ????