You can view a history of emails sent to a customer in the Email History tab. This will include all automatic notifications sent to the customer from Uscreen and it will display when the email was sent and opened by the customer. Specifics of the email message are not visible to admins for security reasons.
Navigate to the customer you want to see an email history for under People > People and click Edit. Under the Email History tab you can see all emails sent to the customer.