I've heard about the new service that Amazon now offers, but I still think that it lacks some major features that MailChimp and others have. I'd recommend you to checkout MailGun, a great service with convenient pricing. What are your sending rates?
@gerdtfhello at my previous job i had some experience with mautic org it is opensource email automation app. Maybe it will help in your case. By the way what are your sending rates?