Hi  nabilabolo,
Check this example. Now please take its reference and correct your code.
Model
public class Student
{
    public string Id { get; set; }
    public string FName { get; set; }
    public string LName { get; set; }
    public bool IsSelected { get; set; }
    public string Email { get; set; }
}
Namespaces
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Net;
using System.Net.Mail;
using System.Threading.Tasks;
Controller
public class HomeController : Controller
{
    // GET: /Home/
    public ActionResult Index()
    {
        List<Student> students = GetStudents();
        return View(students);
    }
    private static List<Student> GetStudents()
    {
        List<Student> students = new List<Student>();
        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        string query = "SELECT Id,FName,LName,IsSelected,Email FROM Students";
        using (SqlConnection con = new SqlConnection(conString))
        {
            using (SqlCommand cmd = new SqlCommand(query, con))
            {
                con.Open();
                SqlDataReader sdr = cmd.ExecuteReader();
                while (sdr.Read())
                {
                    students.Add(new Student
                    {
                        Id = sdr["Id"].ToString(),
                        FName = sdr["FName"].ToString(),
                        LName = sdr["LName"].ToString(),
                        IsSelected = Convert.ToBoolean(sdr["IsSelected"]),
                        Email = sdr["Email"].ToString()
                    });
                }
                con.Close();
            }
        }
        return students;
    }
    [HttpPost]
    public ActionResult Index(List<Student> students)
    {
        //Create a temporary DataTable
        DataTable dtStudents = new DataTable();
        dtStudents.Columns.AddRange(new DataColumn[2] { 
                new DataColumn("Name", typeof(string)),
                new DataColumn("Email",typeof(string)) });
        foreach (Student student in students)
        {
            if (student.IsSelected)
            {
                //Copy the Checked Rows to DataTable.
                dtStudents.Rows.Add(student.FName + " " + student.LName, student.Email);
            }
        }
        string subject = "Welcome Email";
        string body = "Hello {0},<br /><br />Welcome to ASPSnippets<br /><br />Thanks.";
        //Using Parallel Multi-Threading send multiple bulk email.
        Parallel.ForEach(dtStudents.AsEnumerable(), row =>
        {
            SendEmail(row["Email"].ToString(), subject, string.Format(body, row["Name"]));
        });
        return RedirectToAction("Index");
    }
    private bool SendEmail(string recipient, string subject, string body)
    {
        MailMessage mm = new MailMessage("sender@gmail.com", recipient);
        mm.Subject = subject;
        mm.Body = body;
        mm.IsBodyHtml = true;
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.EnableSsl = true;
        NetworkCredential NetworkCred = new NetworkCredential();
        NetworkCred.UserName = "sender@gmail.com";
        NetworkCred.Password = "<password>";
        smtp.UseDefaultCredentials = true;
        smtp.Credentials = NetworkCred;
        smtp.Port = 587;
        smtp.Send(mm);
        return true;
    }
}
View
<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<IEnumerable<_Checked_Row_Email.Models.Student>>" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Index</title>
</head>
<body>
    <%using (Html.BeginForm("Index", "Home", FormMethod.Post))
      {%>
    <table>
        <tr>
            <th>Id</th>
            <th>FName</th>
            <th>LName</th>
            <th>IsSelected</th>
        </tr>
        <% foreach (var student in Model) { %>
        <tr>
            <td><%: student.Id%></td>
            <td><%: student.FName%></td>
            <td><%: student.LName%></td>
            <td><%:Html.CheckBoxFor(m => student.IsSelected)%></td>
        </tr>
        <% } %>
    </table>
    <br /><input type="submit" value="Submit" />
    <%} %>
</body>
</html>