Really Good Emails - A large collection of good product email design.
Seolyzer - Seolyzer is the ultimate SEO tool that provides you with all the information you need to improve your website’s health and performance.
Good Sales Emails - Best sales emails from great companies
SEOmator - SEO website analysis & audit tool
Great Email Copy - A dose of emails from around the web.
Whatsmyserp - Powerful Rank & Serp Tracking. Completely Free.