It's a "push". If I go to your website because I see an interesting article on Hacker news or Twitter I'm unlikely to return for newer articles, even if I'm int

It's a "push". If I go to your website because I see an interesting article on Hacker news or Twitter I'm unlikely to return for newer articles, even if I'm interested I will simply forget. However if you get my email you can push content to me. If you have enough people in your newsletter you can increase your traffic and keep it more consistent, more traffic is more ad revenue. You could even get your newsletter sponsored and make it a source of revenue. I have not worked on newsletters specifically but I can attest that sending emails is generally very effective.