You can view the history of emails sent to a user in the Email History tab. This will include all automatic notifications sent to the user from Uscreen and it will display when the email was sent and opened by the user. Specifics of the email message are not visible to admins for security reasons.
To view it, navigate to the People tab, then under the second People tab, find the user you want to see an email history for and click Edit. Click on the Email History tab to see all emails sent to the customer within the last 6 months.
You will see three columns, Title, Sent On, and Opened On. The Opened On column will have the date and time of when the email was opened by the user, if it wasn't opened, then each unopened email will have a short dashed line.