Two versions of the register of electors, which is compiled in December each year, are now produced, the full register and the edited register. Forms are currently being sent to 80,000 households in the county and people are required, by law, to fill them in.
On the full register everyone's name has to be included for electoral purposes, prevention and detection of crime, fraud and credit purposes. This register is not sold, only supplied to certain people and they are prevented from using the information for marketing purposes.
The edited register, however, is sold to marketing companies so people must opt out of this if they do not wish to receive mail from companies that decide to purchase the register.
Colette Maund, Herefordshire Council's electoral registration services manager, said: "It is important people make sure they opt out of the edited register if they do not want to receive marketing mail from companies.
"People only need to tick a box on their electoral register form to opt out and it can also be done online at http://www.registerbyinternet.com/herefordshire or by calling 0800 1974915."
Further details about the edited register scheme can be found on the reverse of the electoral registration form.