We have added the functionality to determine recipients for emails in version 3.3 (released on December 14th). As part of this, you can set it up so that no-one receives the system emails.
You can find this feature in your Administrative area under Settings -> Site Settings -> Routing of System Emails. If this does not help you and your concerns with email volumes, please contact our support (support@Wildapricot.com) or describe how you'd like it to work in our Wishlist forum.
Giuliano Valentino, Useful Apricot