Pistachio Email Templates - Delicious newsletter templates built for automation
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Transactional Email Templates by Postmark - Open source email templates for use in your SaaS app.
Good Email Copy - Email copy from great companies.
SaaS Email Templates - Responsive HTML email templates for SaaS startups
Really Good Emails - A large collection of good product email design.