The recording industry is taking its anti-piracy message directly to song-swapping consumers, sending notices to thousands of file-traders informing them that they can be easily identified and prosecuted if they continue to download copyrighted material without paying. The warnings are the latest salvo in a strange and disjointed campaign against piracy by the large record companies, and come in the wake of a court’s recent decision that file-trading services may not be held liable for the actions of their customers.