We built our own library to manage transactional email, you define an HTML and Text template, a meta file and then the library inject your data and automaticall

We built our own library to manage transactional email, you define an HTML and Text template, a meta file and then the library inject your data and automatically inline css, it's for NodeJS but you might take some idea from it https://github.com/FGRibreau/node-transacemail https://github.com/FGRibreau/node-transacemail