Sometimes planning for centralized mail delivery mailbox installations can be confusing because there are so many options. So, to help you more easily plan for and design your next installation, here is a quick overview.

There are two main types of equipment:

  • Standard 4C (STD-4C): indoor/outdoor mailboxes that can be mounted in or on walls, or into freestanding mailbox enclosures. This solution has multiple configurations and heights to choose from.
  • Cluster Box Unit (CBU): free-standing, pedestal-mounted mailboxes for outdoor installations. With eight standard configurations, the pedestal ensures mailboxes are always mounted at the required install height.

Similarities & Differences

How do you know which type is right for your installation?

Each mailbox can accommodate certain installation types. Ask yourself a series of questions to determine which type of mailbox will be best suited to your needs.

USPS Approved X X*
Single-family X X
Multifamily X X
Outdoor X X
Indoor   X
Color options X X
Compartment size options   X
Built-in parcel lockers X X
Decorative add-ons X  
Advanced configuration options    X

* While STD-4C mailboxes are USPS Approved, they can also be configured beyond the scope of USPS requirements for use in mailbox installations with private delivery.


Once you’ve determined the appropriate type of centralized mailbox equipment, then you can narrow down your selection based on factors like the number and size of compartments needed for your project.

“Both our Standard 4C mailboxes and our Cluster Box Units are extremely durable, with high-quality construction and safety features designed to protect the contents. Each type of mailbox also has options for built-in and stand-alone parcel lockers, making package delivery secure and convenient for residents, which is especially important in today’s shipping environment.”

– Stacy Kohlmeier, Vice President of Sales & Marketing, Florence Manufacturing

Real-World Example

Let’s say you have an outdoor installation that is in a larger single-family development that wishes to have a secure place for their package delivery, all while staying within the USPS regulations. Which do you choose?

  • Both STD-4C and CBU mailboxes can be used in single-family neighborhoods.
  • Both STD-4C and CBU mailboxes can be used for outdoor installations.
  • Both STD-4C and CBU mailboxes are USPS Approved.
  • STD-4C mailboxes will give you a level of configuration and number of compartments beyond that of the preconfigured CBU mailboxes. They also have greater parcel locker options, so STD-4C mailboxes would be the way to go.

A Word of Caution

When specifying mailboxes in Section 10 Postal Specialties, make sure you’re using current master product specs.

  • STD-4C mailboxes replaced Standard 4B+ mailboxes in 2006.
  • CBU “F” Series replaced the CBU “E” Series in 2005, which replaced the Neighborhood Delivery Cluster Box Unit or NDCBU in 1997.

If it’s been awhile since you updated your product library, we highly recommend you do that ASAP to avoid headaches for your construction team and more work for you down the road.

You can import current BIM views directly into your Revit libraries from our website.

Be sure to visit our Architect Toolkit page for quick access to all these helpful online tools.