Splash Math sends one email per player. Please verify that you have not created multiple players in the app which are not used.

Steps to verify multiple players
  1. Open "Splash Math" app on the iPad and go to the "Home Screen"
  2. Click on the "Profile" button on the "Home Screen".
  3. Check if there are any extra users created which are not being used.
  4. Delete additional players from "Splash Math" which are not being used.