Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Really Good Emails - A large collection of good product email design.
Email Inspire - Discover the best of email design and marketing — Browse email newsletters from top brands.
Good Email Copy - Email copy from great companies.
HTMLEmail.io - Responsive HTML email templates for startups & developers
EmailWay - Collection of the most insightful and informative email newsletters from across a wide spectrum of industries and interests