The Email Logs in the Application Settings keeps a record of each email sent from the system.
From the homepage, click 
to access the Application Settings. Next, click 
.
You can review the emails that have been sent by Alerts, Document Check-Out and Document Share. The columns include:
ID
Email
Event Type
Event Date
Event Note
The Event Type will tell you what emails were processed, delivered and opened. You can filter the grid by email address to view the delivered and opened emails. The Email Logs grid can be exported to Excel, PDF, or Save as Report to My Reports.