Fax machines often have address books and distribution lists. If a fax server is used, the corresponding groupware usually makes it possible to keep similar address books and distribution lists in a central location where they can be accessed by several users. Recipient numbers can be stored in address books so they do not have to be re-entered each time a fax is sent. It is also possible to create a group of recipients using distribution lists and thus send faxes to several people at the same time.

Once programmed, recipient numbers or distribution lists are often no longer checked when a fax document is to be sent. If an unauthorised person changes the address books or distribution lists on a fax machine or in its groupware, confidential information may be sent to the wrong recipients. It is also possible that the intended recipients may not receive urgently needed information. For example, a fax number could be exchanged in the address book, or another recipient could be added to the distribution list without this ever being detected by the person in charge at the organisation in question.