Make sure you are registered with an account by clicking here

If you already have an account click here to sign in

Sign in using your email address and password (Phone Number + PIN Code is no longer supported)

Once signed in you will see your account Dashboard

On the account Dashboard click on "Use Paperless Billing" under the Your Account section

First fill out the "Add New Email Account" section and click the "Add" button

The email address will be added the the "Email Addresses Associated with Your Account"

Click on the "Verify Email" button

Click on the verification link in the email 

Now click on the "Set as Billing Email" now all future bills will be emailed to the given address rather than mailed.