no emails for a user account

As far as I’m aware, it’s not possible via Add New under the Users tab, however, the wp_create_user function will let you create users without an email address:

$username="someuser";
$pass="swordfish";
$new_user_id = wp_create_user( $username, $pass );

You’d have to wrap that in a basic plugin and provide some sort of UI for adding users.