In order to use TurboTax Online, you have to have an email address to set up the account. You can set up 5 seperate accounts using the same email, with different passwords for each account. Many email services allow you to create free email accounts (AOL, Outlook, Yahoo, etc...) or with their permission you could use the email address of a friend or relative, but you will have to be able to verify it, (this is an IRS rule).
You can use TurboTax CD/Download to print and mail returns without an email address. However, again in order to e-file, the IRS does require us to verify an email address.