Really Good Emails - A large collection of good product email design.
Cold Email Hacks - Proven cold email templates and tactics for B2B startups
Good Sales Emails - Best sales emails from great companies
Cold Email Analyzer by Mailshake - Real-time analysis of email subject lines and copy
Great Email Copy - A dose of emails from around the web.
Mailshake - Mailshake lets you build your professional network through a smart and intuitive approach to cold emailing.