Like many customers, you may have questions about the difference between USPS and Private Delivery. U.S. Postal Delivery is when the USPS Letter Carrier delivers mail to each existing tenant compartment in a cluster mailbox. Private delivery is when the letter carrier drops all the mail at one location and in-house personnel distributes the mail.
Due to changes in postal regulations, you may only use these older 4B horizontal mailboxes to replace a current installation of similar mailboxes without modifying the existing wall opening. However, if you do intend to modify the rough opening dimensions during a replacement or remodel, or if you plan to install for new construction, 4C mailboxes will be required.
If you need a large number of mailboxes but have limited wall space, horizontal mailboxes are an economical solution. Because these mailboxes are designed to meet specifications 30+ years old, they should only be installed indoors as they do not include the same weather resistant features or security features as the current 4C mailboxes.