BiggerCake - The data tool that Kickstarter deserves
GetNotify - GetNotify is a free email tracking software solution.
Campaign Monitor Insights - Actionable analytics for email marketing and automation
Bananatag - Find out what happens to your emails after you press send! Add email tracking, attachment tracking, email scheduling and templates to your daily emails.
Snov.io - More leads. More sales. More revenue.
Mailtrack.io - The best email tracking solution I've found. Free