A Robinson list or Mail Preference Service (MPS) list is an opt-out list of people who do not wish to receive marketing transmissions. The marketing can be via e-mail, postal mail, telephone, or fax. In each case, contact details will be placed on a blacklist. Although the purpose of such a list is to reduce unwanted marketing, the principle that "data is only private until someone decides it isn't" indicates it can also generate unwanted marketing.
In the UK, the Mailing Preference Service composes a Robinson list funded by the direct mail industry which collects names and addresses of people who do not want to receive direct marketing. This list is circulated to marketing companies which are then responsible for not contacting people on the list. Although use of this list is governed by the Advertising Standards Authority and the Code of Practice of the Direct Marketing Association, there is nonetheless the potential for names on the list to be used for the opposite of their intended purpose, either accidentally or intentionally.