The USPS is not self-funding, in that it borrows from the US Treasury at a highly subsidized rate of 1.2% to cover its losses. It also doesn't pay any state or local property or real estate taxes, tolls, vehicle registrations, and parking tickets. An interesting article with this information is here:
U.S. Post Office gets an $18 billion gift from taxpayers every year | Fortune
An estimate of the subsidies and legal monopolies that Congress bestows upon the post office is worth $18 billion annually.
We loved Vera, our postal contractor person, when we lived in Tamarind Grove and hope she keeps her job. Her customer service is amazing.