Yes, your account is linked to your email address, so you cannot be a Cotton On & Co. Perks member without one. We recommend signing up with a personal email address that's not likely to change. If you don't have an email address you can sign up for a free email address at:

https://accounts.google.com/signup
https://signup.live.com/signup
https://login.yahoo.com/account/create 

Once you’ve joined the program we'll get in touch via email with any exclusive offers and we'll also use your email address to send you your payday vouchers.