Adam Lane

After hours of trying different manual java code solutions and not being satisfied with results (responsive media query handling issues mostly), I stumbled upon https://github.com/mdedetrich/java-premailer-wrapper which works great as a java solution. But you might be better off running your own "premailer" server. While there is a public api to premailer, I wanted to have my own instance running that I can hit as hard as I want:
https://github.com/TrackIF/premailer-server

Easy to run on ec2 with just a few clicks: https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_Ruby_sinatra.html

git clone https://github.com/TrackIF/premailer-server.git
cd premailer-server
eb init  (choose latest ruby)
eb create premailer-server --sample
eb deploy
curl --data "html=<your html>" http://your.eb.url

Just had this same problem. Thank you for your solution!