Your digital marketing plan for your website should allow you to get the email addresses of people interested in your product or service, you can then market to them via email. This is worth the time and effort it takes because those leads are considered ‘hot’ or at least ‘warm’. That is, they are interested in what you have to offer, so are more likely to buy.
That said, you don’t want to continually shove your offerings at them. First of all you should send them a welcome email – you can set this up to be done automatically. Then you can send them even more information than was on your website in the next email. After that, you can send them more information and a link to purchase the product.