Hemlock - Visualize your competitor's content calendar.
Email Inspire - Discover the best of email design and marketing — Browse email newsletters from top brands.
BrandMentions - Get notified when people mention your brand or competitors
EmailWay - Collection of the most insightful and informative email newsletters from across a wide spectrum of industries and interests
Klue - Klue is competitive intelligence for enterprise sales. We help sales, and the teams who enable them, leverage CI to win more deals.
Really Good Emails - A large collection of good product email design.