The 'switch' to determine if the 'Notify by email' feature is available during the create/edit of any page is controlled by a 'checkbox' in the Settings Area of each GVO.
The default is 'OFF' (so the feature is not available).
If any GVO Manager wants it switched back on then this can only be done via the Settings page on the GVO and only by the GVO Support account. Navigate to the settings area, select the super-user tab, set the checkbox to the desired setting and press Submit.