First, sign in to your email accounts at http://mail.yahoo.com/ or http://mail.yourdomain.com/
Note: Be sure to replace "yourdomain.com" with your domain name.
You'll be prompted to sign in with your Yahoo! ID and password if you aren't already signed in.
To switch between email accounts:
Business Email Welcome Message.
Welcome Menu: Address List
Note: If you're using the original version of Business Email, Classic interface, your available email accounts are listed on the left side of the screen. Select your Business Email account from this list.