Hey Dudley,
Mailchimp is often my go-to just because there's so much that you can do, even if you only need a little bit of it's functionality. I could also suggest Email Marketing. If you find Mailchimp to be a little much, check out their guides. They spend a lot of time building step-by-step for anything you might ever want to do, even if that's just some email campaigns once in a while . :)