On rare occasions, the on-board postal clerk failed to cancel a piece of mail before it left the ship. These uncanceled pieces of mail are not the result of damaged or lost cancellers as with several provsional issues, but were merely the result of negligence by the postal clerks. The items were subsequently canceled with handwritten cancellations (Nachträgliche Entwertungen) upon receipt at the Marine-Postbureau in Berlin.
As of the publication of Pohlmann and Kessing's Handbuch und Katalog der deutschen Marine-Schiffspost und Marinepost 1895-1914 in 2009, ten of these items with handwritten MSP cancellations were known.
The use of handwritten Nachträgliche Entwertungen stopped in early 1900, when the Berlin C1 postal cancel began being used for this purpose.