I have a customer that he is a postmaster for one area and his wife is for another. I asked him about putting flyers on mailboxes. Here is the answer from the post office: Nothing can be put on the receptacle (mailbox)! This means nothing on the flag or taped to the box. Nothing inside either. BUT, you can put things on the post or whatever is holding the mailbox. He called the postmaster generals office to research this and this is the offical word from them. Hope this helps everyone. I thought it was time to take the grey out of this question.