The privilege of sending mail without postage-that is, "free franking," began in England when, in 1652, the Council of State directed that all public packets, letters of parliamentarians, of the Council, of officers in the public service, and of any persons acting in a public capacity, be carried free. The intention behind this right was to facilitate easy flow of opinion and information among public officials and, with a later extension of the privilege, from their constituents.
In the United States, the first Continental Congress adopted the British practice, directing that letters, packets, and dispatches be carried free to and from the members and secretary of Congress (while actually attending Congress), to and from the commander-in-chief of the armies of the United States, or a commander of another army, to and from the heads of the departments of Finance, of War, and of Foreign Affairs. The Postal Act of 1789, which permanently established the United States Postal System, continued the free franking privilege. The Act required, however, that a personal signature be applied to the mail by the sender. This requirement was later modified to allow for machine signatures because of the time needed to hand-frank hundreds of letters.
Widespread abuse of the free frank prompted Congress to abolish the privilege effective July 1, 1873. Upon reconsideration, it passed the Act of March 3, 1877, which authorized official mail to be posted free if it bore the words "Official Mail" and an endorsement with the department's name and stating the penalty for misuse (hence, "Penalty Mail"). In 1891, Congress restored free franking for congressional representatives but placed strict limitations upon its use.