Precancel

A precanceled stamp, or precancel for short, is a postage stamp that has been cancelled before being affixed to mail.
Precanceled stamps are typically used by mass mailers, who can save the postal system time and effort by prearranging to use the precancels, and delivering the stamped mail ready for sorting. Precancels were also used on newspaper wrappers in Canada, Austria and Great Britain. The postal administration will typically offer an incentive in the form of a reduced price for precanceled stamps in volume. Precancels cannot normally be purchased by the general public, although they are often seen in one's daily mail.
A number of nations of the world use precancels, typically in the form of an overprint on definitive series stamps. For instance, in France, the overprint is a semicircle reading "AFFRANCHts. POSTES" (Affranchissements Postes) The United Nations Postal Administration issued one, on Scott catalogue #2, 1 1/2-cent stamp first issued in 1951. Many towns and cities of Belgium and the United States have issued precancels printed with the community's name; in the case of the US, some 9,500 distinct examples of "bureau precancels" are known. Some types of precancels include a date as well.
In the US, overprints have been gradually displaced by special-purpose stamps typically inscribed "bulk rate," "presorted first-class," or "presorted STD."
The Precancel Stamp Society, formed in 1922 from two previously-existing clubs, specializes in the study of precancels. A number of catalogs list all the types of precancels issued in the countries that use them.
Postal training.
Around the early twentieth century, some U.S. business colleges used specially pre-cancelled stamps or stamp-like labels to train students in the handling of stamps.