First make sure you've selected the list to which the email address belongs. (Go to Lists and click on Select List.) Then go to Reports, click on Address Activity Detail. Either select the email address from the displayed list or perform a search for the desired email address using the provided search box. Click Show Activity next to the desired email address in the results list.

You can view both Open/Close statistics and the Activity.

Open/Close statistics will show the campaign name, the date sent, the date and time opened and whether or not the email bounced.

Under Activity, you can see the Activity (sign up, subscriber update, unsubscribe request, etc.) the Date and time of the activity and the IP address where the activity took place.