Transactional Email Templates by Postmark - Open source email templates for use in your SaaS app.
Pistachio Email Templates - Delicious newsletter templates built for automation
Smart Templates by Sarbacane - Get customized email marketing templates from a URL 💌
SaaS Email Templates - Responsive HTML email templates for SaaS startups
MJML - The open source framework for responsive emails
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.