I would recommend checking out https://www.mautic.org/ (free - opensource marketing automation platform self hosted or on AWS) or https://sendy.co/ ($59 - one time fee) hosted on AWS.

The downside is that you will need to have someone build out the HTML email templates. Also, if you are not that technical, you will likely need someone to help you set up these platforms. I'd find someone on Upwork -- $15 to set up, and will definitely be more expensive for the email template.