In November 1897, two German missionaries were murdered by a mob in Shantung Province, China.  In response, German naval forces occupied the port city of Tsingtau, and the German government used the occupation to press the Chinese government for a long-term lease of the port and the surrounding area. In March 1898, Germany and China entered into a 99-year lease under which Germany would control both sides of the entrance to Kiautschou Bay, as well as the islands within. Around this leased territory would be a small neutral zone which would, in effect, also be under German control.

Kaumi was a stop on the German Shantung Railway, which ran from Tsingtau, Kiautschou, through the neutral zone to Tsinan, China.  A Feldpost station, Feldpoststation No. 1, was opened there on 24 November 1900.  This Feldpoststation because a full postal agency on 5 July 1901.

The Kaumi postal agency closed on 31 March 1906.