In the email body, have a link to the response page that passes the UserID as a URL variable:
http://yourdomain.com/response.php?userID=56
you can use the recordset that is used for the email loop to add the Dynamic binding for the user ID in the email.
then on the response [age have a form that they can select the status, and a hidden form element to capture the User ID URL variable, and use that on inserting the status.