I saw this option as well, but I worry that I might get bots or people who don't open the message to subscribe. So if only 10-20% of readers actually open a given email, then at best 25-50 people can benefit from the free tier, max. I'm looking for something a bit more scalable. The next lowest tier of mailchimp costs $13/mo, which is more than 12x what I pay for all my other hosting + domain name costs combined.