Controller
[HttpPost]
public JsonResult GeneratePreview(GenerateDemo Demo)
{
string empCode = "", empName = "", email = "", subject = "", body, signature = "";
var formatbody = "";
foreach (var selectedEmpId in GenerateDemo.selectedIds)
{
var empDetails = (from emp in db.demo 
where emp.inEmpId == selectedEmpId
select emp).FirstOrDefault();
empCode = empDetails.inEmpCode;
empName = empDetails.vcEmpName;
email = empDetails.vcEmpEmailID;
subject = GenerateDemo.subject;
body = GenerateDemo.body;
signature = GenerateDemo.signature;
formatbody = Constants.createEmailBody(empName, subject, body, signature);<-------- I got all data with Html Format i attach html file
}
return Json(formatbody, JsonRequestBehavior.AllowGet);
}
 
 
 
 Html File
 <html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<body>
    <table>
        <tr>
            <td>
                <div style="border-top:3px solid #22BCE5"> </div>
                <span style="font-family:Arial;font-size:10pt">
                    Hello <b>{UserName}</b>,<br /><br />
                    Subject:-<g>{Subject}</g><br /><br />
                   {message}
                    <br /><br />
                    Thanks<br /><br />
                    Siganture <br />
                    {Siganture}
                </span>
            </td>
        </tr>
    </table>
</body>
</html>