What is Black Fax (Disabling of a Fax Machine)?

Last Update: August 9th, 2021

With every invention and piece of technology that comes along, someone finds a way to use it for the wrong reasons.

black fax
Black Fax

Black faxing has become a method that people use to “attack” another fax machine, either disabling it or causing it to run out of toner.

Table of Contents

What is a Black Fax?

A black fax is a technology attack method meant to disable a fax machine.

The purpose of a black fax is to overwhelm the fax machine on the opposite end of a communication, either causing it to run out of ink/toner or mechanically shut down.

This can result in a company or organization being shut down and unable to conduct business.

How is a Black Fax Sent?

A black fax is sent by repeatedly sending a completely black page through a fax transmission over and over to another fax machine.

The black fax will cause excessive use of the victim fax machine’s ink and toner, and in some circumstances may cause it to become overwhelmed and either mechanically or electronically shut down.

At times, a string of pure black pieces of paper are taped together with the intention of continuously feeding the black paper through the fax machine, resulting in an almost endless black fax attack.

When are Black Faxes Used?

Black fax attacks are used primarily for purposes of pranks, retribution, and as denial of service attacks against fax machines.

Documented events of black faxes occurring have happened with:

What are the Costs of a Black Fax?

The costs depend entirely on the type of fax machine used, as well if there is an internet, online, or email fax service in operation.

If there is no hard-copy fax machine, the costs to an organization of receiving a black fax are usually minimal, no more than the time involved in managing junk emails on a daily basis.

If a hard-copy fax machine is used (depending on toner costs as well as wear and tear on the equipment), the costs can be anywhere from $1 per page in toner costs to much higher if part of the printing mechanism is overloaded and needs replacement.

Can a Black Fax be Avoided?

In many cases, there is nothing that can be done to avoid the transmission of a black fax.

There are, however, ways to mitigate the costs involved with a black fax:

  • If you use an online fax service to manage faxes, in many cases you can delete the offending faxes without having to print them. As well, many online fax services will have in place an option to block phone numbers that have transmitted black or junk faxes to your number.
  • If you are at the machine while the black fax is transmitted, you can stop the current transmission.

Is there technology that can prevent black faxes?

Currently, there are no fax machines on the market that can prevent black faxes or that have a black fax filter.
Theoretically, it would not be incredibly difficult for manufacturers to add a filter to most fax machine technology, but regrettably, it has not happened.
Organizations operating larger scale fax servers (such as RightFax or HylaFAX / HylaFAX+) or fax machines that forward to email can easily delete black fax pages without having to print them. However, the phone line resource has still been consumed during the transmission.

Is it Legal to Send a Black Fax?

According to JunkFax.org, “If the fax violates  47 C.F.R. § 68.318(d) which specifies header requirements, it’s illegal, whether it was solicited or not. All faxes must comply with the header requirements.”

In some cases, there is a reason to sue both the companies and the individuals involved (this is not to be taken as legal advice).


This site does not support the use of black faxes for any reason, and this article is intended solely to help people who have been black faxed understand what has happened with their systems and to encourage manufacturers of fax technology put filters in place to detect and avoid black fax transmissions.