Following information is from L. Dominion's article in "American Philatelist": In Turkish "Kachak" means smuggled. since common people in Turkey is poor, an average villager woould try to send mail to his relative in city by a traveller and would therefore pay no postage. Civil guards were aware of this and would search the bags of incoming travellers, seizing unpaid packages and mail. They would then affix it with double the amount of postage using "Kachak" stamps. These searches would bemore strict at times of political unrest and were used most frequently after 1876 during the reign of Sultan Abdulhamid, who had a vast network of security officers whose task was to expose plots against the emperor.
A better term for these stamps should be "Unpaid mail postage stamps." The "Kachak" overprints remained in use between 1865-1890, serving an officila postal function. They are unique philatelic items encountered only in Turkish and Chinese history. Six types of "Kacka" overprints are known, only the first five are encountered on duloz stamps. The framed overprint reads either "Kachak" (Type 1) or "Kachak Postasi" anddenomination (Types 2-5). The ink initially used was black, after 1876 bith blue and res inks were also used. The rare items among following examples are indicated by "**".
Ex Pinar Ozand