USPS Approved Commercial Mailboxes 4C Mailboxes USPS Approved

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.

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.

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.

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.

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.

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.

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”.

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.

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

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.

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.