Sadie Wen is perfect on paper: school captain, valedictorian, and a "pleasure to have in class." It's not easy, but she has a trick to keep her model-student smile plastered on her face at all times: she channels all her frustrations into her email drafts. She'd never send them of course -- she'd rather die than hurt anyone's feelings -- but it's a relief to let loose on her power-hungry English teacher or a freeloading classmate taking credit for...