Thank you for reaching out to the Community! I understand how important it is to keep track of your contacts. I apologize we do not offer a tool that will produce this cumulative report along with these time stamps. This is however a great feature request we have submitted in your account. Have you tried our segmentation tool? Or even our click segmentation? Our segment tool creates a list of who opened or clicked any campaign sent from your account. While the click segmentation tool will automatically add contacts who clicked on a specific link or button to a new list to contact. Both of these options can be used as a workaround to manually exporting and comparing these reports.
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