SmoochBot - Open source on-boarding bot for conversational apps
Really Good Emails - A large collection of good product email design.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Good Sales Emails - Best sales emails from great companies
Hotline - In-app chat,real-time engagement & self-service for your app
Great Email Copy - A dose of emails from around the web.