Commercial Mailboxes
Navigating the world of commercial mailboxes can be complex, especially with strict USPS regulations to consider. Whether you’re a property manager, contractor, or business owner, choosing the right centralized mail solution is crucial for security, durability, and tenant satisfaction. This guide will break down the main types of commercial mailboxes—like 4C and CBU units—to help you make an informed decision for your property.
A Guide to USPS Approved Commercial Mailboxes
For any new construction or major renovation in the United States, the USPS has established standards to ensure mail security and carrier efficiency. Understanding these standards is the first step in choosing the right system.
4C Mailboxes – The Modern Standard
The 4C Centralized Mail Delivery System is the current USPS regulation standard for most new construction. If you are building a new apartment complex, condominium, or commercial facility, you will almost certainly be required to install 4C mailboxes.
CBU Mailboxes (Cluster Box Units)
A Cluster Box Unit (CBU) specifically refers to the free-standing, pedestal-mounted configuration of a centralized mail system. These are the familiar multi-unit mailboxes you see in residential neighborhoods and apartment complexes.
Horizontal Mailboxes
Horizontal Commercial Mailboxes are the recessed, wall-mounted counterparts to CBUs. They are typically installed indoors in a mailroom or in an outdoor protected alcove of an apartment building or office.
Why Choose US Mail Supply for Your Commercial Project?
At US Mail Supply, we understand the unique challenges of commercial mailbox projects. We are more than a supplier; we are your project partner.

Apartment Mailboxes
Shop indoor and outdoor commercial apartment mailboxes: decorative cluster boxes for luxury complexes or locking indoor mailboxes for lobbies or walkways.

4C Horizontal Mailboxes
Steel and aluminum heavy metal construction make commercial USPS approved 4C horizontal mailboxes a tough-as-nails option for apartments, offices, condos, schools, municipal buildings, and multi-family residences.

Outdoor Commercial Mailboxes & CBU's
Outdoor commercial mailboxes for sale at U.S. Mail Supply include curbside pedestal mount cluster mailboxes and large contemporary decorative metal mailboxes.

Decorative Cluster Mailboxes
Unique vintage style lockable decorative cluster commercial mailbox units are a perfect addition for luxury apartment complexes or condos & townhouse subdivisions.

Postal Drop Boxes
Packages and letters are safe in pedestal-mounted secure, locking commercial drop boxes and letter lockers available for sale from U.S. Mail Supply.

Indoor Commercial Mailboxes
Shop recessed, wall-mounted indoor horizontal and vertical commercial-grade mailboxes for small and large businesses and multi-unit residences.

Horizontal Mailboxes
Buy front loading steel & aluminum heavy duty indoor recess wall-mountable commercial horizontal mailboxes for offices, classrooms, apartment lobbies, or businesses.

Vertical Mailboxes
We offer metal commercial vertical mailboxes from 3 slots to 7 slots. Recess wall mount and surface mountable options available.

4C Horizontal Depot Mailboxes
4C Horizontal Depot mailboxes provide an outside private delivery option for universities, campuses, and other business applications. Several slot options available for customization.