Secure and safe mail delivery is a top priority in apartment buildings, residential developments, and business properties. The CBU cluster mailbox is among the best and most popular solutions. Don’t know what a CBU is, how it works, or where to buy a good one? This guide will walk you through the fundamentals—and recommend a trusted source: GoMailboxes. What is a CBU Cluster Mailbox? CBU is an acronym for Cluster Box Unit—a compact, secure mailbox system for distributing mail to several recipients in one location. Rather than individual mailboxes at each door, a CBU concentrates several locked compartments into a single, weather-resistant, heavy-duty unit. They are usually working in: Residential…