Are There Any Regulations That Residential Mailboxes Must Follow?

The USPS has very specific regulations for curbside mailboxes (both single and multi-family) but more lax regulations for wall-mounted mailboxes. For wall-mounted mailbox units, the only requirements that must be met is for the mailbox to be easy to see, safe for the postal employee to access, and to have a working flap that allows mail delivery.

For curbside mailboxes, a set of requirements must be met for the USPS to legally deliver your mail. Mailboxes are designed with these regulations in mind, making your job easier. The same requirements apply to single-unit curbside residential mailboxes and multi-unit curbside mailboxes. Contact your postmaster if you’re unsure if your mailbox will meet USPS requirements.

Placement, Height, and Dimensions. Perhaps the most important requirements are where your mailbox is placed, how high it is, and the size of its post.

• Your mailbox must be just high enough so that the delivery flap (the door) is between 41 and 45 inches from the ground. This is to make the USPS employee’s delivery of your mail easier.
• Your post can’t be larger than 4×4″ if it’s made out of wood, or larger than 2×2″ if it’s made of a tougher material such as aluminum. This is to prevent excessive damage to vehicles should one hit your mailbox by mistake.
• Your mailbox’s post can’t be mounted any deeper than 24 inches into the earth. It also needs to go at least 12 inches into the ground for stability.
• Your mailbox needs to stand between 6 and 8 inches from the road for safety and ease of mail delivery.
• Ensure that your mailbox will be on the right side of the road for the USPS employee. For example, if the other mailboxes on your street are opposite your driveway, yours will need to match this positioning. Otherwise, your mailbox will be on the left of the delivery route, and unable to receive mail.

Design Requirements. Once placement requirements have been met, it’s a good idea to make sure your mailbox meets a few other requirements as well.

• Your mailbox’s address must be visible on the unit. To make sure your address is clear and easy to see, each character must be at least an inch tall. When placing your address on your mailbox (if needed) ensure it’s on the flag side of the box or on the front flap.
• Any accessories included with your mailbox cannot contact the mailbox itself. Accessories can’t be supported by the mailbox, either. This is why newspaper receptacles are typically beside or under a mailbox, connected to the post.
• If your mailbox is locking and with delivery slots, those slots have to be at least 1.75 by 10 inches to allow for delivery of larger mail without folding. The slots must have flaps that turn inward to allow for easy delivery.