I don't know how successful the flier-attached-to-the-mailbox approach is when marketing a business; I only know that it's never enticed me to become a customer, especially when you leave a permanent mark of your message on my mailbox.

May I suggest radio? We'll put together a nice campaign for you and you'll reach a LOT more people in 30 seconds, several times a day, than you will by spending the time and effort to print of a stack of fliers and drive them around neighborhoods.

And you're not going to cheese off the homeowner by putting duct tape on their mailbox.