USPS Mailbox Replacement & Approval
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Ask your local post office to review the proposed replacement before proceeding. Flag changes in location, addresses or compartments, equipment, or carrier access. Even for a like-for-like replacement, confirm authorization rather than assuming it is exempt. Product approval is not approval of a specific site.
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Contact your local Postmaster or delivery supervisor. Ask who handles centralized delivery for your property address.
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Prepare the property address and contact information, unit count, photos, a description of proposed changes, and a site or floor plan showing access, routes, and clearances. Include manufacturer specifications and dimensions, compartment and parcel-locker counts. Ask USPS whether it needs anything else.
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Ask USPS about the project-specific review process and timing before placing nonreturnable orders or removing or installing equipment. No fixed deadline can be promised. Request written confirmation and coordinate temporary delivery arrangements.
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Review carrier and customer access, door clearance, lighting, weather, and gates. Coordinate USPS-controlled hardware with USPS. Have the installer confirm mounting and foundation requirements against the manufacturer's instructions.
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Have an architect, accessibility professional, or building authority review applicable requirements for routes, approach space, reach ranges, and door operation. USPS product approval is not ADA or local-code certification.
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Confirm applicable ratios, usable dimensions, and configuration with USPS and your supplier based on unit count and package needs. Requirements differ; do not assume 4C requirements automatically apply to every CBU or replacement. Consider additional capacity.
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Confirm ownership and responsibilities for installation, tenant keys and locks, cleaning, repairs, and replacement. Ask USPS which components it controls.
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USPS Standard 4C (PDF) is an equipment reference, not authorization for a particular site. Ask your local USPS office which standards apply.
This is a planning aid only, not USPS site approval or accessibility certification.
Frequently Asked Questions
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- • Cluster Box Units (CBUs) are USPS-approved, centralized mail delivery systems typically used for multi-tenant communities, offices, and residential developments.
- • Each CBU features multiple locking tenant doors, parcel lockers, and an outgoing mail slot.
- • These outdoor mailboxes streamline delivery while keeping mail secure.
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- • 4C mailboxes are the USPS standard for new construction and major renovations.
- • They feature larger tenant doors, integrated parcel lockers, and enhanced security compared to older 4B horizontal mailboxes.
- • While 4B units can still be used in some replacement situations, they are no longer compliant for new installations.
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- • USPS-approved mailboxes meet strict postal regulations for durability, accessibility, and security.
- • They are tested to ensure compatibility with USPS delivery standards, which guarantees postal carrier access without requiring special approval.
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- • CBU installation requires anchoring the pedestal base to a concrete pad for stability and aligning with USPS-approved accessibility guidelines.
- • Detailed installation guides are available to ensure compliance and proper setup.
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- • Start by considering the number of tenants and parcel needs.
- • Properties may require outdoor CBUs, indoor 4C horizontal mailboxes, or a combination of both. Our blog explains the differences in detail: CBU vs 4C Mailboxes: Which Is Best for Your Property?.
- • For tailored advice, our team can also help verify USPS compliance and ADA requirements.
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- • Yes! All new installations must use USPS-approved 4C mailboxes or Cluster Box Units. Each product page includes compliance and certification details.
- • Learn more in our article: USPS Regulations and Mailbox Standards.
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- • 4C mailboxes come in multiple configurations, including standard tenant compartments, oversized parcel lockers, and custom layouts to fit mailroom design and tenant needs.
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- • Regular cleaning and light maintenance extend the life of your unit. Wipe down doors and locks, lubricate moving parts annually, and inspect the pedestal base after storms or heavy use.
- • See our care and cleaning guide for detailed instructions.
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• Our warranty covers defects in materials or workmanship for five years on all 4C mailboxes and outdoor CBUs.
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• Most standard units ship within two weeks, while customized or specialty models typically take 2–4 weeks.
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- • Yes, each unit comes complete with all hardware except for the anchor bolts needed to secure the pedestal base to a concrete pad.
- • These bolts are readily available at local hardware stores.
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• No, engraving is included in the price of your mailbox.
• However, please note that engraving may add additional lead time to your order.