A piece of postal stationery is a stationery item, such as an envelope, letter sheet, post card, lettercard, aérogramme or wrapper, with an amount of postage preprinted on it. The preprinted stamp, or 'indicium', is usually at the rate required for a particular postal service, e.g., at the postcard rate for postcards, the domestic letter rate for letter sheets and envelopes, the registered letter rate for registered envelopes, etc. In general, postal stationery is handled similarly to postage stamps; sold from post offices either at the face value of the printed postage or with a surcharge to cover the additional cost of the stationery.
The envelope form may also be called a stamped envelope. In the United States, private post cards (without preprinted postage) are differentiated from postal cards, which are sold by the Postal Service.
Postal services of some countries also offer a form of letter sheet called an aérogramme consisting of a blank sheet of paper with folding instructions and adhesive flaps that becomes its own envelope, and carries prepaid postage at either the international airmail letter rate or at a special lower aerogramme rate. Enclosures are not permitted in aerogrammes.
The first official postal stationery were the 1838 embossed letter sheets of New South Wales. These were followed by the Mulready stationery that was issued by Britain at the same time as the Penny Black in 1840. Since then, most postal services have issued a steady stream of stationery alongside stamps; often the design of the stationery mimics the contemporaneous stamps, though with less variety and lower printing quality, due to the limitations of printing directly onto the envelope.
In emergency situations, postal stationery has been produced by handstamping envelopes with modified cancelling devices; many of the rare Confederate postmasters' provisionals are of this form. Postal stationery can also be overprinted publicly, or by a private overprint.
Although the Scott catalog includes a section for United States postal stationery, and many other country-specific stamp catalogs describe the stationery of their respective countries, the 19-volume Higgins and Gage World Postal Stationery Catalogue is a main reference for stationery worldwide.