Really Good Emails - A large collection of good product email design.
Mail Designer 365 - Discover Mail Designer 365, the easiest way to design mobile-optimized HTML emails, templates and newsletter designs. Your HTML email designer for Mac.
Good Sales Emails - Best sales emails from great companies
MailDeveloper - Advanced editor for responsive HTML emails
Great Email Copy - A dose of emails from around the web.
BeeFree - BeeFree is an all-in-one solution that works anywhere you are.