4C Horizontal Mailboxes and Cluster Box Units (CBU’s) are required for new construction and major renovations. For modifications that affect a wall rough opening, 4C Horizontal Mailboxes are required. For outdoor applications, Cluster Box Units and Parcel Lockers are the most popular choice. 4C Mailboxes are also a good outdoor option when utilizing centralized mail kiosks.
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.