Question: how to use mjml with rails?
Answer: Create new Rails app $ rails new MJML-send-mail $ cd MJML-send-mail. Install MJML $ nvm install 5.0 $ npm install mjml@^2.0. ...  Generate controller $ rails g controller home index. Add gem 'mjml-rails' to Gemfile. 'mjml-rails' allows you to render HTML e-mails from an MJML template.