I added a small tweak to the GetMailContent function to easily add additional fields to the output HTML.  It keeps you from having to modify the long format string.

Fields in this Example :

 var first = HttpUtility.HtmlEncode(HttpContext.Current.Request["first-req"]);
        var last = HttpUtility.HtmlEncode(HttpContext.Current.Request["last-req"]);
        var school = HttpUtility.HtmlEncode(HttpContext.Current.Request["school-req"]);
        var phone = HttpUtility.HtmlEncode(HttpContext.Current.Request["phone-req"]);
        var email = HttpUtility.HtmlEncode(HttpContext.Current.Request[page.FormVariables.EmailFieldName]);
        var message = HttpUtility.HtmlEncode(HttpContext.Current.Request[page.FormVariables.MessageFieldName]).Replace("\n", "<br />");

Create a Dictionary to hold them :

 // create a dictionary to hold our values
        Dictionary<string, string> formResults = new Dictionary<string, string>();

Add Fields :

    // slap data into our dictionary
        // dictionary is fieldName, fieldValue
        formResults.Add("Name", first + " " + last);
        formResults.Add(page.FormVariables.Email, email);
        formResults.Add("Phone Number", phone);
        formResults.Add("School", school);        
        formResults.Add(page.FormVariables.Message, message);
        formResults.Add("Interested In", GetCheckboxStatus());
        // add more fields here!        

Build Form Label / Form Values :

 // build our template string from our fields above
        string valueHTML = string.Empty;
        foreach (KeyValuePair<string, string> formItem in formResults)
        {
            // build our table row with the form field name
            valueHTML += string.Format("<tr><td valign=\"top\"><p><strong>{0}</strong></p></td><td valign=\"top\"><p>{1}</p></td></tr>", formItem.Key, formItem.Value);            
        }

Create mailContent string :

   var mailContent = string.Format(
                                 "{0}<br /><br /><table>{1}</table>",
                                 mailIntroText,
                                 valueHTML
                    );