I forgot my payoneer email address and password

Hello guys!
I reffered my friend for payoneer and he made a new gmail account and signed up for payoneer he saved all the login data in roboform( password and data saving tool) and the he reinstalled the windows without saving the data.
Now how can he knew the email???
If we can know the email address we can recover password and everything.

Till now his card has not arrived and yet not activated.