Mailing envelopes are most often used to enclose a correspondence that is to be sent through the postal system. A mailing envelope is usually made of folded paper and gummed on one flap, and there are hundreds of different envelopes to consider. They are available in assorted styles, including baronial, announcement, catalog, commercial, and booklet. There are also window envelopes that allow a portion of the contents to be revealed, usually the address.
Sending a message encased in folded paper is a practice as old as the origins of paper itself. The earliest mailing envelopes were often a page written on one side of the paper, folded inward, and addressed on the backside. Known as letter sheets, they were sometimes sealed with wax. Before the advent of official post offices, a servant or an independent postal service usually delivered written messages. The first known mailing envelopes officially stamped by a government post office were sent in the year 1608.
Before the industrial age, all mailing envelopes were cut and folded by hand. In 1840, a patented method of cutting the paper allowed for standard sizes to emerge, but folding was still done by hand. The process of standardization allowed the paper to be cut in any number of shapes. A manufacturer could easily produce several flap styles, including pointed, square or commercial. By 1845, a steam powered machine was introduced that could automatically cut and fold several envelopes at a time. Within a short time, an automatic flap-gumming machine was also in use.
The stationery industry recognizes a range of sizes in mailing envelopes, from 0 to 12, with several fractions in between. For example, a standard business envelope is usually a number 10 commercial type. A C-5 is a catalog style envelope large enough to accommodate several sheets of paper without folding. Sizes A-2, A-4, A-7, A-8 and A-10 are all sizes for announcement envelopes.
Direct mail marketers have long understood the advertising appeal of envelopes. The paper chosen for direct mailing envelopes can actually depend on the audience being targeted and the message being conveyed. Additionally, mail marketers consider the envelope a sort of billboard. A salutary message imprinted on the outside is often used to entice recipients to open the piece.
Most post offices will sell pre-stamped mailing envelopes, as well as other mailing supplies. Envelopes are also sold in stationery stores, grocery stores, office supply stores, and online stores. The selection can even include airmail envelopes, padded envelopes made to protect contents, and stiff photo mailers made to protect photographs.