In all things you need to run tests on a recommended safelist. Get or seek reviews by others to check for list responsiveness. Other than that, you need to test your ad. You need to target your ad for that list if you want leads. You need to target your list (choose) for your conversion. All a list offers you is a confirmed email distribution - nothing more - set amount of traffic. Everything else is your copywriting, landing page, and conversion optimization skill.