How To Send Multiple Emails In DotNet

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

using System.Net;

using System.Net.Mail;

public partial class MultipleEmails : System.Web.UI.Page

{

   SqlConnection con = new SqlConnection(@"Data Source=AAPTI-E86BE99D7\SQLEXPRESS;Initial Catalog=MultipleEmails;Integrated Security=True");

   SqlCommand cmd = new SqlCommand();

   DataSet ds = new DataSet();

   protected void Page_Load(object sender, EventArgs e)

   {

       if (!IsPostBack)

       {

           Gridview();

       }

   }

   public void Gridview()

   {

       con.Open();

       SqlDataAdapter ad = new SqlDataAdapter("select * from Users", con);

       ad.Fill(ds);

       con.Dispose();

       GridView1.DataSource = ds;

       GridView1.DataBind();

       con.Close();

   }

   protected void btnSend_Click(object sender, EventArgs e)

   {

       con.Open();

       string email;

       DataTable dt = new DataTable();

       try

       {

           foreach (GridViewRow row in GridView1.Rows)

           {

               if (row.RowType == DataControlRowType.DataRow)

               {

                   CheckBox chk = (CheckBox)row.Cells[3].FindControl("CheckBox1");

                   if (chk.Checked == true)

                   {

                       if (chk != null && chk.Checked)

                       {

                           email = row.Cells[2].Text;

                           SmtpClient smtp = new SmtpClient();

                           smtp.Credentials = new NetworkCredential("prasadtarak1@gmail.com", "mavarick");

                           smtp.Port = 587;

                           smtp.Host = "smtp.gmail.com";

                           smtp.EnableSsl = true;

                           MailMessage msg = new MailMessage();

                           msg.From = new MailAddress("prasadtarak1@gmail.com");

                           msg.To.Add(email);

                           msg.Subject = "Hi frnds i Send a mail.";

                           msg.Body = "How are You.";

                           smtp.Send(msg);

                       }

                       else

                       {

                           Response.Write("<script>alert('Emails are sent Successfully.')</script>");

                       }

                   }

               }

           }

       }

       catch (Exception ex)

       {

           Response.Write("<script>alert('Failed.')</script>");

       }

   }

   protected void CheckBox2_CheckedChanged(object sender, EventArgs e)

   {

       CheckBox chkAll =

           (CheckBox)GridView1.HeaderRow.FindControl("CheckBox2");

       if (chkAll.Checked == true)

       {

           foreach (GridViewRow gvRow in GridView1.Rows)

           {

               CheckBox chksel =

                   (CheckBox)gvRow.FindControl("CheckBox1");

               chksel.Checked = true;

           }

       }

       else

       {

           foreach (GridViewRow gvRow in GridView1.Rows)

           {

               CheckBox chksel =

                   (CheckBox)gvRow.FindControl("CheckBox1");

               chksel.Checked = false;

           }

       }

               

   }

}