I highly recommend https://sendy.co/ https://sendy.co/. It's not open source, but you can host it yourself. In case you need it, you can have multiple brands un

I highly recommend https://sendy.co/ https://sendy.co/. It's not open source, but you can host it yourself. In case you need it, you can have multiple brands under the same installation. It's like a self hosted mailchimp.