disable WP auto responder for registered user.

How can we disable the standard Autoresponder after signup for registered users with only the SUBSCRIBER role..

ie: Multisite (no buddypress) have removed option to register only using a form to bypass the standard WP register.
Now this will work for us as long as the automated Wordpress - username and login details are not sent for Subscribers only.

ie
SEND - YES for administrators that signup.
SEND - NO for subscribers that signup (using a form we generate to add users) this form sends the details we want for subscribers and we do not want the auto WP email sent..