Be aware that these lists may not be for your topic, also these companies charge a fee for renting you the list. It is true that some of these are bona fide companies, that will supply you with a list that can be relevant to your topic. If they are reputable companies then this method of marketing could be beneficial to you.
This method of marketing can be expensive so beware. Opt in "series" email marketing and promotion is another method you can use and it works like this, you offer a free sample of your product, a free gift or a free informative article in your website email list. This works well with a pop up window, when your visitor submits their name and e mail address they then receive a free gift.
Now they have subscribed to receive a "series" of emails on your topic, the best "series type" is to offer free and valuable information on your topic. If they have a problem that is relevant to your topic, then advise them on how to solve the problem. Give a good quality " email series" and this will build a trusting relationship with your customer. This method can be personalized and automated once you have built the basic structure. Most businesses are looking for the best strategy to attract buyers.