Free drinks for all with Starbucks Rewards

Who: Starbucks, your ubiquitous corner coffeehouse, whose now infamous loyalty program is studied in MBA programs across the world.
What’s Working: Simple value proposition, who wouldn’t want to give a free Starbucks drink to their friend?
What’s Not: This referral email assumes some familiarity with Starbucks Rewards, e.g. what do Bonus Stars tangibly mean for me? I’d also argue that the invitation diagram on the black background is more important that the green drinks illustration and the two should be flipped.