It is illegal to open or place anything in a persons personal mailbox. the law is very clear in this area. its more important today than ever before for this reason......theft identity. bills arrive at your mailbox with vital personal information. your soc. sec. number, your account numbers, and of course checks in the mail. ciminals frequently canvass neighborhoods, looking in mailboxes, hoping to be able to use your information for their benefit. believe me, a neighbor will call the police to check out your suspicious activities. place the flyer on the flag of the mailbox. it will still be noticed and you will be legal. end