The last Postmaster General , Prince Karl Alexander von Thurn und Taxis , lost his office with the Empire 's dissolution on 6 August 1806 .
Postmaster General 's postal authority continued as the Frankfurt - based Thurn - und - Taxis Post until the unification of Germany .
The last Postmaster General , Prince Karl Alexander von Thurn und Taxis , lost his office with the Empire 's dissolution on 6 August 1806 , but his postal authority continued as the Frankfurt - based Thurn - und - Taxis Post until the unification of Germany .