Click on the "My Account" link at the top-right of the page. You will need to provide an Overstock Email Address and Password (this email address is the same that we need for the "Pay for an Auction" page).
Click the "Account Info. & Password Change" link located below the welcome message.
Your E-Mail will appear below the Login Information header.
Click on the "Options" link located on the top-right corner of the page.
Click the "Edit Contact Information" link located in the Personal Information column on the left (you will be prompted to sign in).
The Review My Account Information/Yahoo! ID Card: page will appear. Under the Member Information section, you will see a list of available Yahoo email addresses.
The first email address listed (next to Yahoo! Mail Address: is usually the email address you need to use to enter checkout. However if you have other email addresses listed, choose the one marked as primary.