'Postage Able' was a British series of three commando and naval beach reconnaissance operations along the Normandy coast of German-occupied France (31 December 1943/21 January 1944).

'Postage Able I' was a commando undertaking to survey the area between Arromanches and La Rivière on 31 December 1943. 'Postage Able II' was another commando beach reconnaissance operation of the Normandy coast of German-occupied France between Pointe de Hoc and Vierville on 17 January 1944.

'Postage Able III' was designed to survey the landing beaches proposed for 'Neptune' (iii), and was based on the use of the midget submarine X-20, which spent four days off the French coast to complete this task between 18 and 21 January 1944). Periscope reconnaissance of the shoreline and echo-soundings were performed during the days, and each night the X-20 approached the beach to despatch two divers, who swam ashore and collected beach samples. The divers went ashore on two nights to survey the beaches at Vierville sur Mer, Moulins St Laurent and Colleville sur Mer in what became the 'Omaha' Beach sector used by the US Army. On the third night, the divers were scheduled to go ashore off the estuary of the Orne river in what became the 'Sword' Beach area, but by this stage fatigue (the crew and divers had been living on little more than Benzedrine tablets) and the worsening weather caused the skipper to shorten the operation and return to the X-craft’s 'mother', the submarine Dolphin, on 21 January.

The Allies built two scale models of the landing beaches, one used by the War Department in room 474 of the Metropole Hotel, London, and a duplicate in Prime Minister Winston Churchill’s room in the Cabinet War Rooms.

At Cairnryan, just to the north of Stranraer in south-western Scotland, a 'life size' reproduction of the beaches was constructed. This allowed the planners to assess the effectiveness of the current landing techniques and the movement of men and machinery over the terrain.