Really Good Emails - A large collection of good product email design.
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
Good Sales Emails - Best sales emails from great companies
HubSpot Free Email Marketing - Powerful drag and drop email marketing in the HubSpot CRM
Great Email Copy - A dose of emails from around the web.
Quokka (formerly Kryptowire) - The gold standard in SAST, MAST, IAST, and more!