Really Good Emails - A large collection of good product email design.
growth.email - Weekly curated email with the best growth marketing articles
Good Sales Emails - Best sales emails from great companies
Great Email Copy - A dose of emails from around the web.
GrowthHackingIdea.com - One short, curated growth hacking idea a day to your email
Email Inspire - Discover the best of email design and marketing — Browse email newsletters from top brands.