Deutsche Reichspost - German Imperial Mail

In the Girl in the Glass, James has a clever idea - send postcards back to the United States, letting selected people know where their journey to find the Obturavi led them. As Bruce explains:

“These Postkarten will serve as a beacon, our signal flare, telling the Clypeate where to look in case things go awry.”

This involves a trip to the Deutsche Reichspost. The Reichspost (German Imperial Mail) was Germany's national postal service from 1871 to 1945. Operating under the Reich Postal Ministry in Berlin, it functioned as a government monopoly overseeing mail and telecommunications throughout the country. 

Besides mail delivery, the Deutsche Reichspost was a savings bank, a motorized transport service for mail delivery, and in some rural areas, provided the only public transportation. The Reichspost also controlled telegraph, telephone, cable, and provided technical maintenance to the German Broadcasting Corporation. They even provided commercial telegraph and telephone services to ships and aircraft. 

Upon the Nazi regime's rise to power in 1933, they maintained the Reichspost's structure and services while leveraging it for propaganda and control. Notably, on July 25, 1941, the Reichspost introduced the world's first postal code system. The purpose of this innovation was to streamline mail sorting and delivery, particularly in response to the growing demand and challenges posed by World War II. The United States finally introduced postal codes, officially known as ZIP Codes, on July 1, 1963.