eventually, it can become impossible to trace the original file. Another increasingly popular method of distributing Warez is via one-click hosting websites. In the early 1990s, warez were often published on bulletin boards that had a warez section. Rise of software infringement Unauthorized copying has been an ongoing phenomenon that started when high quality, commercially produced software was released for sale. Whether the medium was cassette tape or floppy disk, cracking enthusiasts found a way to duplicate the software and spread it without the permission of the maker. Bootlegging communities were built around the Apple II, Commodore 64, Atari 8-bit family, ZX Spectrum, Amiga, Atari ST and other personal computers. Entire networks of BBSes sprang up to traffic illegal software from one user to the next. Machines like the Amiga and the Commodore 64 had an international network, through which software not available on one continent would eventually make its way to every region via bulletin board systems. It was also common in the 1980s to use physical floppy disks and the postal service for spreading software, in an activity known as mail trading. Prior to the sale of software that came on CD-ROM discs and after hard drives had become available, the software did not require the floppy disc to be in the drive when starting and using the program. So, a user could install it onto his/her computer and mail the disk to the next person, who could do the same. Particularly widespread in continental Europe, mail trading was even used by many of the leading cracker groups as their primary channel of interaction. Software copyright violation via mail trading was also the most common means for many computer hobbyists in the Eastern bloc countries to receive new Western software for their computers. Copy-protection schemes for the early systems were designed to defeat casual duplication attempts, as "crackers" would typically release a copied game to the "pirate" community the day they were earmarked for market. A famous event in the history of software copyright policy was an open letter written by Bill Gates of Microsoft, dated February 3, 1976, in which he argued that the quality of available software would increase if "software piracy" were less prevalent. However, until the early 1990s, software copyright infringement was not yet considered a serious problem by most people. In 1992, the Software Publishers Association began to battle against this phenomenon, with