An easy way to (locally) test HTML email templates in multiple clients. A free alternative to existing paid email test services. You only need to configure an SMTP server or use GMail with an app specific password (recommended).
Clone this project and fill in the env variables in docker-compose.yml with your own data. Next run docker-compose up -d (or docker compose up -d) and wait for everything to build. After that you can go to https://localhost:3000 and see a basic form.
Fill in the recipient's email a subject (optional) and the HTML code of your e-mail template. Click send and check your mail design in the e-mail client.
I haven't put in error handling yet so if nothing happens check the response of the /api call.