Worldwide postal services have tried numerous experiments over the years at increasing revenues. Most common has been the experiment of advertising with postage stamps. This experiment was first made almost coincidentally with the issuance of the first postage stamp. The Mulready envelope was issued together with the Penny Black as the world's first piece of postal stationery and private companies quickly began advertising on part of the writing page of the stationery. These letter sheets were then sold at discounts from the postage value to people willing to have such advertising with their mail. In the late nineteenth century, New Zealand experimented with placing printed ads on the backs of postage stamps. As these ads could only influence the buyers of the stamps and only then until the stamps were glued to the envelope, they enjoyed limited success and never had government sanctioned use elsewhere. The greatest success for postal advertising has been as se tenants and booklets and have been a mainstay of postal issues of Western European countries such as Germany, France and Belgium for many years. These issues have always been very popular with specialists in these areas and provide many interesting collecting nuances, such as used setenants on cover, which can be very rare. Our USPS has eschewed revenue raising methods such as this which is hard to understand in a country as devoted to capitalism as we are. But our post office has had a conservative issuing policy in all phases. We have rarely issued semipostal stamps (stamps with a charity surcharge) though these has also been a mainstay of Western European postal issues for almost one hundred years
