[jbusnengo]

Originally Posted by ratinox

https://faq.usps.com/s/article/ZIP-Code-The-Basics

A full ZIP+4 does not necessarily identify a business address, only when the business has specifically requested a unique ZIP+4.

In the hopes of putting this question to bed so we can get back to the topic of the thread, the USPS maintains a database of every address in the USA and whether that address is residential or business. A company can pay for access to that database. See https://postalpro.usps.com/address-q...-indicator-rdi.