Mail kind the only possibility for the contact was outward just in the time of the cold war for many people in communist governed lands. No matter mail kind was nothing else than one art exchange which occurred above the letter way. There it seemed reasonable for creative people to decorate own post also with own stamps. And neither the test of the post, nor the saving of postage stamp stood in the foreground. The letter should come, artist's stamps for the purposes of this mail kind is stuck always in addition to normal postage. But one will not be able to exclude it that some need the "kick".
My definition: “Eine artist's stamp in the sense of the mail kind is an expression of opinion of an artist on the smallest space. The technologies used in addition reach from the elastic stamp (even multicolored) about the purely copied brand up to unique specimen stamp which were produced partially or completely by hand.
The spectrum of the grasped subject areas reaches from the personal expression of opinion, political, cultural nature up to the most different artistic directions which one can fancy.
Mail kind was if you want in such a way, however, the precursor of the Internet at that time and lives on also even today, in spite of quick computers.