One of the few functions of FedGov that is both useful and Constitutional.
Mend it, don’t end it.
“The Postal Clause was added to the Constitution to facilitate interstate communication as well as to create a source of revenue for the early United States.[2][3] There were some early disagreements as to the boundaries of the Postal Power. John Jay, in a letter to George Washington, opined that the postal service should not be burdened with the responsibility for handling newspaper delivery, and also suggested that the Post Office be placed under the supervision of the executive branch (a suggestion which later led to the creation of the Post Office Department).[4] Thomas Jefferson feared that the postal service would become a source of patronage and a waste of money. Jefferson also expressed doubt at granting Congress the power to designate post roads, as he considered road building to be a state responsibility.”
(From https://en.m.wikipedia.org/wiki/Postal_Clause )
Jefferson could see it coming a mile away.
There is nothing preventing privatization. There is every reason to do so to end this jobs program with an unpayable pension obligation.