3500 Series 4B+ vertical mailboxes are USPS approved for replacement / retrofit purposes only. These units are for indoor use only in small multi-family buildings & apartments. You may choose recess mounted or surface mounted versions. If you have any questions about compliance or installation info please give us a call and we’ll help fill in the blanks.Understanding the 4B+ Replacement Standard
It is crucial to understand that 4B+ vertical mailboxes are not for new construction. The current USPS standard for new installations is the larger 4C system. Our 3500 Series vertical mailboxes are specifically designed to replace older, existing 4B style units in buildings where a larger 4C system is not feasible. Always consult with your local Postmaster before ordering to confirm compliance for your project.
3500 Series: Key Features & Options
Our 4B+ compliant vertical mailboxes are constructed for security and durability, available in 3, 4, 5, 6, or 7-door configurations.
- Construction: Heavy-gauge extruded aluminum with striated doors and trim to resist scratching.
- Compartment Size: 16 ¼” H x 5 ½” W x 6 ¾” D.
- Locks: Each unit includes 5-pin cylinder tenant locks (two keys per door) and a master door. Choose between:
- USPS Access: Prepared for your local Post Office to install their master Arrow Lock.
- Private Delivery: Comes with a private-use master lock for internal mail distribution.
- Finishes: Durable powder-coated finish available in Aluminum, Brass, Bronze, Sandstone, or Green.
- Outgoing Mail Option: An outgoing mail slot can be added to the left-most door for a small upcharge.
Installation Options
Our vertical mailboxes wall mounted units offer two installation methods to suit your building’s needs.
- Recess Mounted: Installs into a wall cavity for a flush, professional finish. Requires a 7 ½” wall depth.
- Surface Mounted: Installs directly onto the surface of a wall. Protrudes 7 ½” from the wall. Ideal for retrofitting where recessed installation is not possible.
Why Choose US Mail Supply for Your 4B+ Replacement?
We provide the correct, compliant products and expert guidance to ensure your replacement project is a success.
- Compliance Experts: We understand the nuances of USPS regulations, including the critical distinction between 4B+ (replacement) and 4C (new construction) standards.
- High-Quality Construction: We offer durable, secure mailboxes built with heavy-gauge aluminum and reliable locking mechanisms to protect your residents’ mail.
- All Configurations Available: We stock the full range of door configurations (3-7 doors) and all available finishes to match your building’s aesthetics.
- Clear Information: We provide detailed product data sheets and installation instructions to ensure your project goes smoothly.
Frequently Asked Questions About Vertical Mailboxes
Can I use a 4B+ vertical mailbox in a new apartment building?
No. The USPS requires the new 4C standard for all new construction and major renovations. 4B+ mailboxes are only approved for replacing existing 4B units.
What is the difference between a recess mount and a surface mount vertical mailbox?
A recess mount sits inside a wall cavity, while a surface mount is attached to the face of the wall. Your choice depends on whether your wall can accommodate the required depth for a recessed installation.
Do these mailboxes include a slot for outgoing mail?
They do not come standard with one, but you can add an outgoing mail slot to the left-most door as a customizable option when you place your order.
Who installs the lock on the master door?
If you choose the “USPS Access” option, your local Post Office will provide and install their official Arrow Lock. If you choose “Private Delivery,” the unit will arrive with a standard commercial lock already installed.