On April 21, 1646, Elector Friedrich Wilhelm issues postal regulations establishing regular postal service between Berlin, Münster, Osnabrück, Kleve and Königsberg. The new decree stems from the Elector's interest in staying well informed of the current status of the peace negotiations in Osnabrück and Münster to end the Thirty Years' War.

At the same time, the decree grants private individuals (in particular merchants) the right to have their mail transported by the electoral postal system. Friedrich Wilhelm thus ignores the emperor's postal monopoly granted to the Postmaster General of the House of Thurn and Taxis.