Modify Reverse Auction Factory Email Notification Process

Background: Currently Users can choose (1) service "Categories" to display in their User Profile and (2) a "Service Area" radius in miles. The same "Categories", as are available in the User Profile, are available to designate new auctions within Reverse Auction Factory. Also, currently when a User "Follows" such a Category in Reverse Auction Factory, they will automatically start to receive email notifications of any new auctions created in that Category. Project: We would like to have Users automatically Follow/Unfollow Categories in Reverse Auction Factory Based on their Profile Setting and to limit those email notifications to auctions within the User's selected "Service Area" radius.