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Pneumatic post or pneumatic mail is a system to deliver letters through pressurized air tubes.

It was invented by the Scottish engineer William Murdoch in the 19th century and was later developed by the London Pneumatic Despatch Company.

Pneumatic post systems were used in several large cities starting in the second half of the 19th century ( including an 1866 London system powerful and large enough to transport humans during trial runs – though not intended for the purpose ), but were largely abandoned during the 20th century.