| An envelope is a packaging product, | | | | reply mail, or freepost (business reply |
| usually made of flat, planar material | | | | mail). Some envelopes are designed to be |
| such as paper or cardboard, and designed | | | | reused as the return envelope, saving |
| to contain a flat object, which in a | | | | the expense of including a return |
| postal-service context is usually a | | | | envelope in the contents of the original |
| letter or card. The traditional type is | | | | envelope. The direct mail industry makes |
| made from a sheet of paper cut to one of | | | | extensive use of return envelopes as a |
| three shapes: the rhombus (also referred | | | | response mechanism. |
| to as a lozenge or diamond), the | | | | Up until 1840 all envelopes were |
| short-arm cross, and the kite. These | | | | handmade, each being individually cut to |
| designs ensure that when the sides of | | | | the appropriate shape out of an |
| the sheet are folded about a delineated | | | | individual rectangular sheet. In that |
| central rectangular area, a | | | | year George Wilson in the U.K. patented |
| rectangular-faced, usually oblong, | | | | the method of tessellating (tiling) a |
| enclosure is formed with an arrangement | | | | number of envelope patterns across and |
| of four flaps on the reverse side, | | | | down a large sheet, thereby reducing the |
| which, by virtue of the shapes of sheet | | | | overall amount of waste produced per |
| traditionally used, is inevitably | | | | envelope when they were cut out. In 1845 |
| symmetrical. | | | | Edwin Hill and Warren de la Rue obtained |
| When the folding sequence is such that | | | | a patent for a steam-driven machine that |
| the last flap to be closed is on a short | | | | not only cut out the envelope shapes but |
| side it is referred to in commercial | | | | creased and folded them as well. |
| envelope manufacture as a '"pocket"' - a | | | | (Mechanised gumming had yet to be |
| format frequently employed in the | | | | devised.) The convenience of the sheets |
| packaging of small quantities of seeds. | | | | ready cut to shape popularized the use |
| Although in principle the flaps can be | | | | of machine-made envelopes, and the |
| held in place by securing the topmost | | | | economic significance of the factories |
| flap at a single point (for example with | | | | that had produced handmade envelopes |
| a wax seal), generally they are pasted | | | | gradually diminished. |
| or gummed together at the overlaps. They | | | | As envelopes are made of paper, they are |
| are most commonly used for enclosing and | | | | intrinsically amenable to embellishment |
| sending mail (letters) through a | | | | with additional graphics and text over |
| prepaid-postage postal system. Envelopes | | | | and above the necessary postal markings. |
| are useful. | | | | This is a feature that the direct mail |
| Window envelopes have a hole cut in the | | | | industry has long taken advantage of -- |
| front side that allows the paper within | | | | and more recently the Mail Art movement. |
| to be seen. They are generally arranged | | | | Most of the over 400 billion envelopes |
| so that the sending address printed on | | | | of all sizes made worldwide are |
| the letter is visible, saving the sender | | | | machine-made. The envelope-machine |
| from having to duplicate the address on | | | | making industry is dominated |
| the envelope itself. The window is | | | | internationally by Winkler and |
| normally covered with a transparent or | | | | Dunnebier. |
| translucent film to protect the letter | | | | Post office requirements |
| inside. In some cases, shortages of | | | | Post offices prefer envelopes to be |
| materials or the need to economize | | | | rectangular rather than square, as this |
| resulted in envelopes that had no film | | | | reduces the amount of sorting that is |
| covering the window. One innovative | | | | needed to line up all the envelopes with |
| process, invented in Europe about 1905, | | | | the addresses reading the same way. |
| involved using hot oil to saturate the | | | | Australia |
| area of the envelope where the address | | | | In Australia, post office-preferred |
| would appear. The treated area became | | | | envelopes have four boxes printed in |
| sufficiently translucent for the address | | | | orange ink at the bottom right-hand |
| to be readable. A typical use for window | | | | corner where handwritten postcodes are |
| envelopes is courtesy reply mail. | | | | meant to be written. Character |
| An aerogram is related to a lettersheet, | | | | recognition software is used to read the |
| both being designed to have writing on | | | | postcode number. |
| the inside to minimize the weight. Any | | | | The Reply Paid is a system whereby a |
| handmade envelope is effectively a | | | | customer may reply to a sender, with the |
| lettersheet because prior to the folding | | | | sender bearing the cost. Specially |
| stage it offers the opportunity for | | | | printed envelopes are used, with the |
| writing a message on that area of the | | | | sender's address and the words "Reply |
| sheet that after folding becomes the | | | | Paid" with an authorization number. The |
| inside of the face of the envelope. | | | | stamp is replaced by three black |
| The "envelope" used to launch the Penny | | | | stripes. The sender pays the postage |
| Post component of the British postal | | | | plus a fee to the postal authority. The |
| reforms of 1840 was a lozenge-shaped | | | | customer may write the Reply Paid |
| lettersheet. But if desired, a separate | | | | envelope out by hand. |
| letter could be enclosed with postage | | | | Other countries use freepost as well, |
| remaining one penny, provided the | | | | although the envelope designs required |
| combined weight did not exceed half an | | | | by those countries' postal authorities |
| ounce (about 13 grams). This was a | | | | differ widely from that described above. |
| legacy of the previous system of | | | | For example, in the U.S., Reply Paid is |
| calculating postage, which partly | | | | called Business Reply Mail. |
| depended on the number of sheets of | | | | Envelopes in the Soviet Union were |
| paper used. | | | | printed with something like the common 7 |
| A "return envelope" is a preaddressed, | | | | segment LCD display, to assist the user |
| smaller envelope included as the | | | | to write the 6-character postcode |
| contents of a larger envelope and can be | | | | directly in machine-readable format. |
| used for courtesy reply mail, metered | | | | |