Consumers around the world are burdened by large amounts of unaddressed junk mail. Attaching “No junk mail” stickers to mailboxes offers a simple solution for protecting against unwanted ads. Presumably, the use of such stickers can be increased if consumers deliberately decide either for or...

Behavioral economists have argued that incentives can backfire. In a field experiment, we distribute “no junk mail” stickers to more than 800 households. We introduce information, monitoring, and rewards in treatments. We do not find evidence of motivation crowding out.