What are the United States Postal Office (USPS) standards curbside mailboxes need to adhere to?

The United States Postal Services (USPS) has a specific guideline standard that must be followed for both manufacturers of approved mailboxes and the installation of such mailboxes for curbside use. These standards are there to ensure safety and ease of delivery for the postal carrier during curbside delivery. Curbside delivery refers specifically to delivery performed from the mail truck itself, where the driver does not leave the vehicle and is not applicable to mailboxes for door delivery service (wall mounted mailboxes).

USPS Standard 7C

The latest standard, USPS-STD-7C was released on September 14th, 2015. It covers both the installation requirements as well as the mailbox specifications itself for Non-Locked Mailboxes and Locking Mailboxes. The USPS also publishes an annual list of all manufacturers whose mailboxes have been approved for the latest standard which can be found on the Postal Bulletin.

Brief Overview of Standard 7C

- In order to be approved, manufacturers must follow the external and internal specifications provided by the USPS.
- The incoming mail slot must be 41 to 45 inches above the surface of the street and no more than 6 to 8 inches away from the curb.
- The mailbox post should be made from wood that is no larger than 4x4 inches and should not be buried deeper than 24 inches in the ground. Steel or aluminum pipes may also be used as long as they are less than 2 inches in diameter.
- The house number must be clearly visible on the front right-hand side of the mailbox with letters at least 1 inch tall.
- The mailbox flag can be any color except green, brown, white, yellow, or blue. A high visibility color such as red or fluorescent is preferred.
**A full list can be found here: USPS-STD-7C 

Curbside Mailbox Installation

What is the Difference Between Full Service and Limited-Service?

A Full-Service Mailbox is designed to have both an incoming as well as outgoing mail area. Limited-Services Mailboxes are designed to receive mail only. The postal carrier will not stop at a Limited-Service Mailbox unless they have items to be delivered.

What are some of the Testing Requirements in order to be listed as a USPS-Approved Mailbox?

Here is a list of some of the more interesting testing requirements in order for a mailbox to be approved. For the complete list please refer to the actual USPS Standard 7C document. [link to standards pdf]
- Capacity: the amount of mail that can fit inside
- Operational Requirements: how many cycles (1 cycle = open/close) can it withstand
- Water-Tightness: will it prevent the contents from getting wet
- Salt Spray Resistance: is the material resistant to corrosion and material fatigue caused by road salt
- Abrasion Resistance: how easily does the coating/paint come off
- Structural Rigidity Requirements: how easily will the mailbox deform under a specific load
- Impact Test: can it withstand impact without noticeable deformation, cracking of the material, or creating hazards with sharp edges
- Security Test (locking mailboxes only): how easy is it to break into with either the use of knives, pry bars, pliers, etc...

Which Companies offer Approved Residential Mailboxes?

All USPS Standard 7C Approved Mailboxes

Mail Boss (Epoch by Design)

Whitehall Products

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