The mail arrives, but sadly the bulk of it is not for you . The letters are addressed to former inhabitants or ex-lovers and you would rather not deal with them.
Return mail to the sender by drawing one line diagonally through the address. When you place the misdirected mail in the post-box, the post-people will know to deliver the marked mail back to its sender. Your hands are clean from with-holding or tampering, it is possible the addressees will eventually receive their mail, and you have gotten all $00.42 out of that stamp.