USPS Approved & 
High 
All Aluminum Front & Rear
Free Expert Project Competitive Price Match
Manufacturers build 4C mailboxes as centralized mail delivery systems that meet USPS STD-4C standards. Developers install these systems in new construction and major renovation projects that require centralized mail delivery. These mailboxes are most commonly used in multi-tenant and commercial settings. USPS STD-4C standards apply nationwide, but local postmasters control final delivery approval. Always confirm requirements before installation.
Manufacturers offer horizontal 4C mailboxes in recessed, surface mounted, and free-standing configurations. Developers select the mounting style based on building layout and delivery requirements. Mounting style determines whether USPS approves the installation. Developers use recessed systems for USPS delivery and reserve surface or free-standing systems for private delivery.
Recessed mounted units install flush within a framed wall opening. Developers and contractors select this option during new construction or major renovation projects. Manufacturers design recessed 4C mailboxes to meet USPS STD-4C specifications for centralized delivery. Local postmaster approval is still required before activation.
! USPS APPROVED WHEN INSTALLED PER STD-4C AND CONFIRMED BY THE LOCAL POSTMASTER
Surface mounted 4C mailboxes attach directly to the wall surface and typically include a matching enclosure. Property managers and building owners use surface mounted units when USPS delivery is not required.
! NOT USPS APPROVED – PRIVATE DELIVERY ONLY
USPS carriers do not deliver mail to surface mounted 4C mailboxes. Always confirm delivery requirements before selecting this option.
Free-standing 4C horizontal mailboxes are housed in a Free Standing Depot Cabinet and are used in spaces where wall mounting is not possible. Facilities use free-standing units for controlled-access environments with internal or private delivery systems.
! NOT USPS APPROVED – PRIVATE DELIVERY ONLY
Buildings that require USPS delivery should select recessed mounted systems instead.
4C mailbox systems support either USPS delivery or private delivery, depending on the mounting style and building requirements. Developers select recessed mounted 4C mailboxes when USPS delivery is required. USPS installs and controls the Arrow lock, and the local postmaster must approve the installation before mail service begins.
Property managers select surface mounted or free-standing 4C mailboxes when private carriers or internal staff handle mail delivery. USPS does not deliver to these configurations.
Developers should select a configuration that meets current tenant needs and allows for future growth.
Manufacturers offer 4C horizontal mailboxes in
single-column and double-column layouts.
The number of tenant doors directly impacts capacity.
As a general planning reference:
USPS often requires one parcel locker for every five tenant mailboxes in STD-4C installations. Requirements vary by location, so confirm the final ratio with the local postmaster before finalizing your layout.
Access style affects how staff service and maintain the mailbox system. Front-loading units are accessed from the tenant side and are typically installed in interior mailrooms. Rear loading units let carriers access compartments from a secured service corridor.When choosing between front and rear loading designs, consider the following factors:
Manufacturers build 4C horizontal mailboxes for daily use in high-traffic environments. Most systems are constructed using
heavy-duty aluminum with reinforced doors and hardware, making them suitable for daily use in busy, multi-tenant environments.
When comparing finishes and security features, buyers often look for the following:
Installation height determines whether tenant compartments
meet ADA reach requirements. Coordinate placement with
the architect and contractor and confirm local accessibility
requirements before finalizing the layout.
Depending on how high they’re mounted, certain door-high configurations can make ADA compliance easier. Strategic numbering and placement can also improve accessibility for tenants.
Planning these details early helps avoid rework and ensures long-term usability.
Plan installation early to avoid delays and ensure the mailbox system integrates smoothly into the building design.
4C Horizontal Mailboxes are perfect for apartments, condos, office buildings, military bases, and residential developments. Made entirely of aluminum, they are USPS-Approved and come in both front and rear loading options. These 4C units and parcel lockers comply with USPS-STD-4C specifications and are mandatory for new construction and major renovations since October 2006.
