Create new site, but without configuring email for that domain
I would like to setup a site on my ISPConfig installation, but I don't want to use the email feature, since the domain is already using Google's Apps for hosting the emails. The problem I have is that when I create a new site, it automatically requires to create a user (and a email) in order to create the user credentials. But since I don;t want to use ISPConfig to configure any emails for this domains, I don't see where I can disable email service for that specific domain I want to create.
Any idea how to do this?