Handling of mail often exposes postal workers to dust, especially when the mail bags are opened. Sometimes, dangerous chemicals may be split, and 
there are also electrical hazards that workers have to face. So postal systems have always been interested in mechanizing post offices. Between World War 1 and II, many postal systems introduced conveyor belts to move mail between handling points. The letter sorting office at Mount Pleasant in London was one of the most highly mechanized in the world Gradually, machines were introduced to prepare mail, and sort small letters from the bigger ones. There were also machines to stamp the date on letters and to put them neatly into sacks In modern, mechanized sorting systems, workers sit at a keyboard while letters are mechanically passed in front of them. Approximately fifty to sixty letters each minute are processed by the operator. Based upon the code entered by the operator, the letters are segregated into different bins, and then removed, bundled and dispatched by the postal workers
