BLACK-Mail, a certain rate of money, corn, cattle, or other valuable, anciently paid in the north of England to certain persons who were allied with robbers and plunderers, in order to be by them protected from pillage. This composition with the protectors and supporters of thieves was prohibited by the 43d Elizabeth, cap. 13, and it seems to have been early checked in the English border counties. But in the Highlands of Scotland the exaction of black-mail from the lowland borderers continued in spite of every effort to put it down, till after the Rebellion of 1745.
Black-mail is defined by Dr Jamieson "a tax or contribution paid by heritors or tenants, for the security of their property, to those freebooters who were wont to make inroads on estates, destroying the corns, or driving away the cattle." Rob Roy Macgregor, one of the most noted of these, overawed the country as late as the year 1743, and frequently robbed the Duke of Montrose's factor of the rents after they had been collected from the tenants. Spelman thinks that this illegal imposition received the name of black-mail from the poverty of those who were thus assailed, and as being paid in black money, not in silver; and Du Cange adopts this idea with little variation, stating that while brass money is called blanque or blanche maille, or white money, by the French, the Saxons and English denominate
it black, in opposition to silver, which they account white money. But the more probable opinion is, that the epithet black is here used in a moral sense, to indicate the illegality or iniquity of the exaction. Wachter, however, defines "black-mail" tributum pro redimenda vexa, deriving it from the German "placken," rexare, exagitare, whence "bauren-placker," rusticorum exagulator; and Schilter says that "black-en" signifies predari.