I'm building a web app for sending newsletters with AWS Simple Email Service https://github.com/mailbadger/app. It's still a work in progress, I'm still a couple of features away from releasing a beta version, but basically you'll be able to import your subscribers, group them, create templates and create and send campaigns. After that you can see statistics such as bounces, complaints etc.

I'm using Go for the backend and React on the frontend, along with MySQL and NATS for message queueing.