The Messages menu has a link to the Find Recipient tool that makes it easy to locate a particular constituent and view their history and subscriptions.
To locate this feature, click on the Contacts tab in the Messages left navigation menu and then choose Find Recipient.
Enter an email address into the search field to look up a specific Messages recipient. The results will list all constituents associated with that email address at the top.
On this screen, you can view a list of any messages recently sent to the recipient (and whether they were delivered, opened, or clicked), and their mailing list subscriptions and unsubscribe history.