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USPS Approved Commercial Mailboxes


More Info About USPS Approved Commercial Mailboxes

Salsbury Industries carries a complete line of commercial mailboxes for U.S.P.S. delivery. Commercial mailboxes are designed for multi-tenant applications where the U.S. Postal Service will be delivering the mail to each bank of mailboxes. Choose from this group of products when the U.S. Postal Service will be delivering the mail. On front loading mailboxes, your local postal official will visit your site upon request and install a master postal lock that allows access to the unit by a U.S. Postal Service employee through one master door opening. Commercial mailboxes for U.S.P.S. delivery include cluster box units (CBUs), 4C horizontal mailboxes, 4B+ horizontal mailboxes, 4B+ vertical mailboxes and a variety of additional products. These products are commonly used in apartment complexes, commercial buildings, residential developments, condominiums and many other applications.


Outdoor Commercial Mailboxes


The cluster box unit (CBU) is the most popular mailbox designed for multi-tenant centralized outdoor mail delivery. Cluster mailboxes are United States Postal Service approved and are ideal for multi-family housing units, apartment complexes, commercial buildings, schools, colleges, government facilities, military bases, and other residential and commercial developments. 

CBUs include a pedestal and are available in 4, 8, 12, 13, and 16 mailbox door configurations (plus parcel lockers for package delivery). These units are extremely secure with heavy-duty cam locks and anti-fish plates to prevent mail tampering. Designed with elegance in mind, Salsbury Industries also offers regency decorative cluster mailboxes that come with a decorative top and decorative pedestal cover. Cluster box units are available in sandstone, bronze, white, green, black and gray. 





Wall-Mounted Commercial Mailboxes


4C horizontal mailboxes are the industry standard for recessed mounted centralized mail delivery. Unlike pedestal mounted mailboxes such as the CBU, 4C horizontal mailboxes are typically recessed into the wall. Salsbury Industries also offers 4C horizontal mailboxes in surface mounted and free-standing models. Available in aluminum, bronze, sandstone and black, 4C horizontal mailboxes are made of heavy-duty aluminum with stainless steel hardware and are ideal for commercial buildings, multi-family housing units, apartment complexes, government offices, military bases, universities, schools and other commercial and residential developments.  

Designed for replacement and retrofit installations, Salsbury 4B+ horizontal style commercial mailboxes are another commonly used wall mounted commercial mailbox. The Salsbury 4B+ horizontal style mailbox is made entirely of aluminum and is available as a recessed mounted unit. 4B+ mailboxes are also available as vertical units that come in 3-door, 4-door, 5-door, 6-door, and 7-door configurations. The 4B+ vertical mailboxes are available in aluminum, bronze and sandstone and can be purchased as recessed mounted or surface mounted units.





USPS Commercial Mailbox Requirements


USPS commercial mailbox requirements dictate that all new construction and major renovations must meet current USPS specifications. Commercial mailboxes for U.S.P.S. delivery include cluster box units (CBUs) and 4C horizontal mailboxes. 4B+ horizontal mailboxes and 4B+ vertical mailboxes can be used for retrofit applications only. All USPS approved mailbox products are commonly used in apartment complexes, commercial buildings, residential developments, condominiums and several other applications.  


Commercial Mailboxes for Sale


Salsbury industries offers a complete line of commercial mailboxes for multi-tenant applications.  Most orders ship within 1 to 2 business days and volume discounts are available. You can order your Salsbury commercial mailboxes via our customer service department or online. If you have any questions about our commercial mailboxes please contact us via email, online chat or toll free at 1-800-624-5269.

FAQ Categories

Questions & Answers

USPS Commercial Mailboxes

Do mailboxes need to be USPS approved?

All mailboxes must be approved by the United States Postal Service for USPS delivery. Salsbury mailboxes are USPS approved and meet or exceed US Postal Service requirements and specifications. Visit this page to learn more about USPS mailbox requirements and specifications.

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How do I know if a mailbox is USPS approved?

If your mailbox is USPS approved, it will have a label or marking that says, “Approved by the Postmaster General” or “Approved by the U.S. Postal Service”.

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What is centralized mail delivery?

Centralized mail delivery is a delivery system in which the U.S. Postal Service mail carrier delivers mail for multiple residences at one central location.

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What is a commercial mailbox?

A commercial mailbox is a type of mailbox that allows a mail carrier to deliver mail to multiple tenants in one centralized location. Cluster mailboxes and 4C horizontal mailboxes are the most popular types of commercial mailboxes.

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Where to buy commercial mailboxes?

Salsbury Industries carries a complete line of USPS approved commercial mailboxes. Commercial mailboxes for USPS delivery include cluster box units, 4C horizontal mailboxes, 4B horizontal mailboxes, 4B vertical mailboxes, and several additional products. Check them out here.

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What are the requirements for USPS approved commercial mailbox installations?

The July 2020 edition of the U.S. Postal Service’s National Delivery Planning Standards included a Guide for Builders and Developers.

  • All new or remodeled apartment buildings must install USPS approved 4C centralized mailbox equipment. 4B horizontal mailboxes and 4B vertical mailboxes are to be used for retrofit applications
  • 1 parcel locker is required for every 5 mailbox compartments
  • Mailboxes and parcel lockers in apartment buildings must be placed reasonably close to the entrance in vestibules, halls, or lobbies. The mail carrier also needs to be able to service the mailboxes without interference from swinging or open doors
  • The Postal Service may authorize the installation of approved 4C mailboxes in exterior walls of buildings as long as they are not installed directly on the street or a public sidewalk.

For more information, visit our United States Postal Service Mailbox Regulations and Specifications page.

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Are commercial mailboxes weatherproof?

Out of all the mailboxes designed for multi-tenant centralized outdoor mail delivery, the cluster box unit (CBU) is the most popular. Salsbury’s durable and corrosion-resistant CBU’s are constructed of heavy-duty aluminum and stainless steel hardware with a powder coated finish that will stand up well to harsh weather conditions. One compartment in each Salsbury cluster mailbox is labeled “Outgoing Mail” and includes a weather protection flap.

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How do I pick the right USPS commercial mailbox?

Mailboxes.com has many USPS approved commercial mailboxes available for purchase. You will find ample information about each mailbox’s features, options, installation instructions, and more on each mailbox’s product page that will help you select the perfect mailbox to suit your needs. You can also use our website’s Live Chat feature to discuss any questions you have with a customer service representative or view our summary sheet here for assistance in selecting the right USPS commercial mailbox for your application.

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What’s the difference between 4C and 4B+ mailboxes?

4C horizontal mailboxes are designed for higher security and are required for new construction and major renovations. 4B horizontal mailboxes and 4B vertical mailboxes are for direct one-to-one replacements. 4B horizontal and 4B vertical mailboxes are permitted for replacement use if no significant changes are required to the rough wall opening where the existing wall-mounted mailboxes are currently installed (though you should always check with your local Post Office to be sure). If that isn’t the case, 4C mailboxes must be used.

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What are parcel lockers?

A parcel locker is a lockable compartment designed to hold packages that will not fit in a standard mailbox. Parcel Lockers can be independent units or integrated into Cluster Box Units or 4C horizontal mailboxes.

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How do parcel lockers work on cluster box units and 4C mailboxes?

When a U.S. postal mail carrier is unable to fit a package into a standard mailbox compartment, they will place your package in a parcel locker. The carrier will then leave a key to the open parcel locker in your mailbox.

To get your package out of the parcel locker, you simply need to use the key the mail carrier has left in your mailbox to unlock the parcel locker. The key will have a tag that indicates which locker contains your package. Once you have unlocked the parcel locker and retrieved your package, the key capture system will secure the parcel locker key in place so that it can’t be removed. Only a U.S. postal mail carrier will be able to remove the key with a master key. If you’re still unsure of how parcel lockers work, consult this helpful video.

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What is an arrow lock?

An arrow lock is a lock used by the USPS so that mail carriers can have access to commercial mailboxes and can deliver mail. This type of lock is also referred to as a “Master Access Postal Lock”.

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How do I get a USPS approved lock installed?

To obtain a USPS approved arrow lock, you will need to contact your local post office branch. Then you can arrange for United States postal personnel to come and install the lock for you.

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Who delivers to USPS approved mailboxes?

Mail carriers employed by the U.S. Postal Service deliver to USPS approved mailboxes.

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Which USPS approved mailboxes can I use for indoor use?

Salsbury Industries manufactures USPS STD-4C horizontal mailboxes that are ideal for indoor use. 4B horizontal mailboxes and 4B vertical mailboxes can be only used for indoor retrofit and replacement applications.

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What is the mailbox configurator used for?

You can use Salsbury Industries’ Mailbox Configurator to help you determine the ideal number of mailboxes and parcel lockers required based on your specific needs. The mailbox configurator will also allow you to create detailed layouts for your mailbox project. Check it out here.

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