Black fax

A black fax is a prank or malicious attack involving the transmission of a document containing primarily or entirely black pixels via fax machine. The intent is to waste the recipient's toner (or ink), paper, and potentially clog the fax machine. Early black faxes were created by simply photocopying a black sheet of paper repeatedly. Modern instances might involve digital image files transmitted as faxes using internet fax services or fax servers.

The impact of a black fax can range from a minor annoyance to a more significant issue depending on the volume of black faxes received and the capabilities of the recipient's fax equipment. A large number of black faxes can quickly deplete toner and paper resources, causing disruption and expense. In some cases, receiving a continuous stream of black faxes could potentially be considered a form of denial-of-service attack, rendering the fax machine unusable for legitimate communications.

While not generally illegal in itself, sending a black fax with malicious intent or as part of a larger coordinated attack could potentially violate laws related to harassment, vandalism, or disruption of communications services. The sender's intent and the scale of the disruption are key factors in determining any legal ramifications.