The same administrator email for all the network blogs

Hi,
I run a WordPress multi-site and would like to create new blog where the administrator email will always amount to an email, mine. This is because I want to create a new user posts and author I can set to have its own email.
When I try to put my email on the child site will not let me because it says that email is already in use.
How can I do to assign the same administrator email to multiple site within blogs network?

Thanks