Transactional Email Templates by Postmark - Open source email templates for use in your SaaS app.
SaaS Email Templates - Responsive HTML email templates for SaaS startups
Smart Templates by Sarbacane - Get customized email marketing templates from a URL 💌
Pistachio Email Templates - Delicious newsletter templates built for automation
MJML - The open source framework for responsive emails
Email Template Generator - Email templates for your important relationships