They are also presented with a range of offers and need only sign to one to be entered into a prize.
Advertisers can also ask further questions to understand more about a visitor once their offer is selected. Prospect data can be checked against advertisers' own databases and every opted-in email is validated.
The has been used by Volvo, KLM and travel search engine Henoo.com, which has benefited from a 16% click-through rate on its welcome email.
Mark Smith, chief executive of TMN Media's parent company TMN, said: "Third party online lead generators account for a large proportion of leads but have to date only been able to provide relatively unfiltered prospects to mass-market advertisers.
"Consumers suffer from scams such as being forced to sign up to all advertisers once registered, to be eligible for prize draws. As a result, the inclination of consumers to participate is eroding because they are being misled or flooded with irrelevant communications.
"Plum Offers is evidence that the industry is capable of evolving its practice and satisfying advertiser and consumer needs. It combines the strong incentive of a guaranteed prize, high levels of accountability and the benefits of shared costs for advertisers."