No purchase necessary link: https://www.starbuckssummergame.com/?utm_source=announcement&utm_medium=email&utm_campaign=0807_summer_game_2#oamoe
You can request 3 game spins per day (2 spins from selecting “after 2 pm” and 1 spin from selecting “before 2 pm”)
Should be good for some free stars, at least.