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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.

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GetNotify - GetNotify is a free email tracking software solution.

Exceedra - Exceedra is a global enterprise solution that offers consumer goods companies the tools they need to get ahead of the competition.

Mailtrack.io - The best email tracking solution I've found. Free