Ask HN: RSS to Email suggestions (as a publisher)

I am working on a Ghost blog that publishes an RSS feed. I want to allow readers to subscribe by email, i.e. receive an email with the latest blog post each time a new post is published. I'd like to automate this if at all possible rather than create my own campaign with Mailchimp or similar.

My thought was, since RSS is automatic, that would be a good hook for some sort of tool to email subscribers, but all I can find on Google are tools for readers rather than publishers. Any ideas on how to accomplish this?