The Mailbox Trick (Trick Series #2)

Kerby's great aunt's typical, boring birthday gift is a package of fancy stationery for writing thank you notes. Ugh! So, when Kerby stalls on writing thank you's, it feels great to write nasty letters to his enemies. But the joke's on Kerby when his cousin accidentally mails the letters. Now he's got to get them back any way he can!