Which Mailbox is Right for My Project?

At Mailbox Emporium, we get asked this important question many times each day. While we are always happy to discuss this personally with our customers, we thought it would be helpful to provide a quick overview. All of the information below is based on the latest USPS regulations, so we take the guesswork out of it for you. If you prefer to discuss this by phone, just give one of our mailbox specialists a call at 888-352-9194.

New Construction

For new construction, there are only two types of mailboxes that are USPS approved for centralized mail delivery – cluster mailboxes and 4C mailboxes. See below to identify which of these models will be the best fit for your new construction project.

Important – New USPS regulations now require one parcel locker for every five mailbox doors, unless there is another form of USPS approved package delivery on site (package room, electronic package lockers, etc). If the mailbox(es) you are planning on purchasing does not meet this 1/5 ratio, additional parcel lockers should be added. Also, it is important to always consult with your local USPS office to determine the best location for your new mailboxes prior to installing.

Cluster Mailboxes (CBU’s) – Pedestal-mounted cluster mailboxes are the most popular selection for outdoor centralized mail delivery. Each cluster mailbox is USPS approved and offers safe and secure access for mail and package delivery. Cluster mailboxes are available in 4, 8, 12, 13, and 16 door configurations and offer high security as well as exceptional durability.

4C Mailboxes – 4C mailboxes are required for indoor mail delivery in new building projects or for major renovations. 4C mailboxes come in a wide variety of configurations ranging from 1-20 mailbox doors and can be customized for your specific project needs. 4C mailboxes can be recessed into the wall, surface mounted to the wall, or free standing in a cabinet.

Existing Building

When it’s time to replace mailboxes in an existing building, we always recommend upgrading to either 4C mailboxes or cluster mailboxes (as shown above). However, we understand that sometimes this may not be possible due to wall depths, wall widths, wall materials, or available space for outdoor delivery. In this case, there are other options for replacement and retrofit installations. The 4B mailboxes below are USPS approved only if being used to replace the same style existing mailboxes. This should not affect the existing rough opening of the wall and the wall should not be modified to accept the new 4B mailboxes. For major renovations, 4C mailboxes or cluster mailboxes are required.

4B Horizontal Mailboxes


4B Vertical Surface Mount


4B Vertical Recessed


If you have questions regarding any of the information provided above, please don’t hesitate to give one of our mailbox specialists a call at 888-352-9194 or email us at sales@mailboxemporium.com.