Mailing flyers can be expensive for small business or entrepreneurs who want to advertise their services. To avoid postal costs, many local advertisers would rather place flyers in mailboxes. However, there are laws you have to consider before doing so.
The United States Postal Service, or USPS, was founded in 1775 as a division of the government, which means USPS has the right to make legal restrictions.
According to postal regulations, no flyer or anything else mailable can be be put in a mailbox without proper postage.
Even if you put a stamp on your flyer, it is still illegal to put the flyer in a mailbox unless it was mailed through the post office.
It is also illegal to affix flyers, stickers, or anything else to a United States Postal Service collection box.
The only exception to the rule is a mail slot on a door or building. USPS regulations don't cover this, so you can insert a flyer into a mail slot.