Emails spam all admin

When a new user try to register an email is sent to all admins users.
This email is sent when a new user registering a new account in a company withtout vendor_admin role define.
Didi would like to be the only person who can receive the email.

So the email should only be sent to the admin of the application.
Under this email we will add a checkbox to say "Send also registration email to users with the admin role" with true by default.