Unfortunately Mulready's design was not well-received by the public and various cartoonists and artists produced lampoon versions. However it was recognized that an innovative and powerful communication adjunct piggybacking on the basic letterpost service had become available, and over the next 50 years or so millions of pictorial envelopes with a wide variety of motifs and designs were processed by postal services worldwide.
As an art form the early genre produced low- and high-minded works ranging from the comic and satirical through commercial and industrial advertising to the promotion of socially worthy causes such as free trade, world peace and brotherhood, and the abolition of slavery. Examples exist of pictorial propaganda envelopes with patriotic motifs produced by both sides during the American Civil War.
The enthusiastic use of this piggyback medium continued throughout the second half of the 19th century until postal administrations worldwide began to authorize the use of picture postcards, which were first approved and offered for sale at all Post Offices in the Austrian Empire on 1 October 1869.
In a sense this was the beginning of the end of the heyday of the pictorial envelope. Producing a card with an illustration on it, whether executed by hand or by a mechanical printing process, is less involved than producing it on an envelope. A card is flat and usually rectangular like a canvas; an envelope starts out flat, but the sheet from which it is formed has to be shaped and then folded. The extra difficulty which producing multiple printed envelopes entails eventually led to the establishment of the commercial envelope printing and overprinting industry which, like commercial envelope manufacture, is perforce an economy-of-scale activity, which means it is at its most economically efficient when the print run is very long.
This was the situation prevailing until the advent of digital electronics in the late- 1960s/early-1970s. The convergence of this technology with telephone technology led to the development of the social-change engine known as the Internet by the early 1990s, so that by the end of the 20th century it had become increasingly common to find households with a digital computer and a sheet printer. By employing suitable software the printer could be used to customise machine-made envelopes, each with a unique composition of colorful digitised text and graphics.
In principle this meant even the most graphically challenged could employ the pictorial or illustrated envelope medium and produce a work categorizable as mail art.
Some works, whether or not produced with the aid of a computer, might be constructed with postal distribution in mind; others might make use of the postal service to facilitate a collaboration or work of 'correspondence art' between artists.
When the electronic telecommunications network known as the Internet gave rise to e-mail art, conventional mail-art artists came to refer to the international postal service as the 'paper net'. When a group of these artists are in some way linked through their works they are collectively referred to as a Mail Art Network.
The Mail-Art Network concept has roots in the work of earlier groups, including the Surrealist and Fluxus artists and the notion of 'multiples' or artworks manufactured as editions. Most commonly, Mail-Art Network artists have made and exchanged postcards, designed custom-made stamps or 'artistamps' , and designed decorated or illustrated envelopes.But even large and unwieldly three-dimensional objects have been known to have been sent by Mail-Art Network artists, for many of whom the message and the medium are synonymous.
Fundamentally, mail art in the context of a Mail Art Network is a form of conceptual art. It is a 'movement' with no membership and no leaders.
The 1980s anarcho-punk duo APF Brigade individually recorded each copy of their first mail-order only cassette release Live Brigade. Each was therefore an unique artifact, and thus could arguably be considered to have been a part of the mail art movement (see also Cassette culture).
The International Union of Mail Artists (see external link) is a group of mail-art artists individually practicing in several countries. Anyone can join just by saying so; in this way the group is merely unified conceptually.
Mail-art artists were among the first to see and use the networking possibilities of the World Wide Web when it appeared in 1992 to bring graphics to the previously text-oriented Internet. But at the same time, the Internet offered nothing new to them (as it is certainly not possible to send objects over the internet). Mail-art artists, like graffiti and poster artists, often work anonymously or collectively under aliases. There are few stars of the mail-art circuits, but among the those with the highest profile are: