On 26 January 1869 he published an article in Austria's leading paper Neue Freie Presse "Über eine neue Art des Korrespondenzmittels der Post", (i.e. "About a novel means of postal correspondence"), proposing that all envelope-size cards, whether written, produced by copying machine or printed, ought to be admitted as mail if they contained not more than 20 words including address and sender's signature and showed a 2-Kreuzer postage stamp.
Austria-Hungary's Postmaster General Vincenz Baron Maly von Vevanovič took up the idea, and in September 1869 the "Correspondence Card" was officially introduced in Austria by ministerial order.
[3] From 1 Oktober 1869 Austria's General Post Office was to issue postal cards for very brief messages, which, at a prize of two "Neukreuzers" (new Kreuzers), were to be delivered to any place within the dual monarchy, irrespective of the distance involved.
[4] Britain in fact very soon followed the Austrian example and introduced the postcard just a year later, and so did the North German Federation, together with the states of Württemberg and Baden; in 1871 Switzerland, Luxemburg, Belgium, the Netherlands, Denmark and Canada followed; 1871-74 Rumania, Russia, the Scandinavian countries, Spain, Japan, Itay, Chile and France followed whereas early as 1777 "L’Almanach de la Petite Poste" had reported about an early and short-lived forerunner(in translation): "Nowadays, cards which are decorated with engravings are sent by post as compliments or best wishes upon the most diverse occasions, with messages that anyone can read.
The realization of his proposal through the Austro-Hungarian post office made Herrmann a well-known personality in Europe, but later his authorship of the postcard was contested.
[9] Stephan, however, had not actually proposed the postcard, but a postal sheet the size of a money transfer form, stiffer than letter paper and slightly larger than the usual envelope, with an imprinted duty stamp and available at all post offices.
In fact, Germany later introduced not Stephan's postal sheet due to its lack of privacy but a post card on precisely the Austrian model.
[11] Herrmann's quite different area of interest lay in the field of ethnology: He was an important collector of the folksongs of Carinthia, the Austrian state where he had come from.