(57) An ink pump (40) for a high speed mailing machine is disclosed. The ink pump 40 pumps ink from an ink reservoir 41 to an ink pad of an ink pad device 36. The ink pump 40 comprises a deformable chamber and valves (232, 234) which cooperate to pump ink upon compression of the chamber and release of the compression. The pump (40) comprises an input and an output, and the valves comprises a one way valve 232, e.g. a duck bill valve, disposed at the pump input which closes upon compression of the chamber and opens upon release of the compression, and a one way valve 234, e.g. a duck bill valve, disposed at the pump output which opens upon compression of the chamber and closes upon release of the compression. Duck bill valves (232, 234) enable the pump (40) to be disposed in any attitude including horizontal. These valves (232, 234) may be disposed entirely within the deformable chamber, which may comprise a sleeve 230 of elastic material.