Körner is a municipality in the Unstrut-Hainich-Kreis district of Thuringia, Germany. History Within the German Empire (1871-1945), Körner was part of the Duchy of Saxe-Coburg and Gotha. Körner is the place with the highest postal code number in Germany - 99998. References Unstrut-Hainich-Kreis Saxe-Coburg and Gotha