Step 1: Go to https://purecharity.com/ and SIGN IN to your Pure Charity account.
Step 2: From your user dashboard, click 'Notifications' in the left-hand menu. From here you can choose what communication you desire to receive.
Deselect any notification you would not like to receive (or select any you would), then click . That's it. Changes are immediate and you should no longer receive undesired communication.