Djember - Banjoewangi Netherlands Indies / Dai Nippon 1943 Permission cachets

Official mail had to be handed in open for inspection. The senders did not have postal freedom.
Correspondence was only allowed on post cards. Certain organisations were allowed using envelopes, but each envelope needed a special cachet to show they had permission.
There are many different cachets by different organisations. Even the Japanese Army was involved. This resulted in four permission cachets on this cover.

Cover is depicted in book P.R. Bulterman - Poststempels Nederlands Indie 1864 - 1950 Page 399