Have you ever heard of a data broker? Whenever you pay with a credit or debit card, or gain "points" with the stores' loyalty card, that spending information goes on your profile. That profile amasses huge data about your spending habits.
This trade in personal information is big business with the companies involved, ranging from vast multinationals to small firms. Some conduct straightforward activities, such as collating lists of names and contact details to sell. Others combine multiple sources of data to create rich intrusive profiles of individuals.
The free Mailing Preference Service (MPS) lets you opt out of unsolicited, personally addressed mail. The MPS, suggests that when you received unwanted catalogues, in the first instance, you should contact the business directly. You can write or email the business and ask them to remove your personal data from their records and any affiliates. Explain how it’s making you feel, receiving all this unsolicited mail.
If you register with the MPS they will do that for you. On their website there is a
complaint section where they ask for you to scan or send in the mail you’ve received. Then their team will contact the organisation and give them 14 days to respond. When they speak to the organisation they make the point that it’s going to save them time and money, and reduce waste, if they only correspond with the people who want to receive the information. (This is only for the UK) Other countries have similar organisation.
The best way of all, of avoiding unsolicited junk mail through your letterbox, is to pay for your purchases in cash. It's anonymous.