We mostly do this through our blog to pick up traffic like @JoshDoody mentioned below, but we try to capture the email by pay-walling (which I was MASSIVELY against at first) with a subscription page popup.
From there we drip feed them value before ever mentioning our own product.
However, without a decent backlink profile it can seem like you're not getting anywhere, so do bear in mind that SEO is the other side of the coin here.
We mostly do this through our blog to pick up traffic like @JoshDoody mentioned below, but we try to capture the email by pay-walling (which I was MASSIVELY against at first) with a subscription page popup.
From there we drip feed them value before ever mentioning our own product.
However, without a decent backlink profile it can seem like you're not getting anywhere, so do bear in mind that SEO is the other side of the coin here.