Effective 1 May 1899, the rate for mail originating in a German colony and addressed to another colony or to Germany was reduced to the inland rate.  In late 1899, steamships on the Linie Hamburg-Westafrika were provided with auxiliary markings to be applied to mail received on board the ships while in a colony and addressed either to another colony or to Germany.  As the origin of many mail items was not obvious on the face of the items, this ensured that subsequent post offices would not attempt to apply postage due charges believing the items were from a foreign point of origin.

The markings can be found in an unknown number of variations.  One- and two-line versions are known, in black, blue, violet, or red ink.  Handwritten notations are also known.