definition
strict definition
post office
A node where shipping and delivery services are provided to users by a governmental mail system.
A post office is any primary collection or delivery site for government-controlled mail (other than a simple mailbox). Post offices usually contain mail sorting facilities as well.
The site must be a primary collection or delivery location for government-controlled mail. A simple mailbox is expressly excluded even though mail can be deposited there.
Mail sorting is common but not mandatory. A shipping station separately identifies a commercial retail outlet for package services.