WordPress MU

Hi there,
I accidentally somehow removed a user from my blog. When I attempted to add the user again I got an error saying that the email was already being used...and it is on another blog on the site.
How can I re-add my user account to the blog using the person's same email?

thanks!

Are you trying to add the user to the site again, or just to one blog? It sounds as though you may be trying to add it at the admin level, since the user must already exist to add them to a blog on the site...