Some companies that send junk mail include a "business reply" envelope. This allows the junk mail recipient to send a "reply" through U.S. mail at the originator's expense.
In fact these business reply envelopes can be filled with heavy junk and given to the U.S. Postal Service in order to impose additional postage costs on the junk mailer (perhaps discouraging them from further junk mailing). If a person did that could he be found liable for damages in a civil action? Or does it run afoul of any criminal statute? Are there any examples of either?