how to use implement a 1 sec delay while sending 1000 emails.........

protected void btnsubmit_Click(object sender, EventArgs e)
    {
        string toemail = null;
 
        MailMessage ebatch = new MailMessage();
        SmtpClient mySmtpClient = null;
        OleDbConnection DBConnection = null;
        OleDbCommand DBCommand = null;
        OleDbDataReader Datareader = null;
        string SQLString = null;
        DBConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + Server.MapPath("~/App_Data/cust.mdb"));
        DBConnection.Open();
        SQLString = "SELECT EmailID FROM Customers ";
        DBCommand = new OleDbCommand(SQLString, DBConnection);
        Datareader = DBCommand.ExecuteReader();
        while (Datareader.Read())
        {
            toemail = Convert.ToString(Datareader["EmailID"]);
            ebatch.From = new MailAddress("confirmation@testsite.com");
            ebatch.To.Add(toemail);
            ebatch.Subject = "sample message";
            ebatch.Body = "this is a test message";
            // mail server//
 
            mySmtpClient = new SmtpClient(ConfigurationManager.AppSettings["SmtpRelay"]);
            mySmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
            mySmtpClient.UseDefaultCredentials = true;
            try
            {
                mySmtpClient.Send(ebatch);
                Response.Write("&lt;i> Email Sent to  " + toemail + "!</i>");
                System.Threading.Thread.Sleep(1000);
 
            }
            catch (Exception ex)
            {
 
                Response.Write("the following exception occurred:" + ex.ToString());
                // check with InnerException
                while (ex.InnerException != null)
                {
                    Response.Write("--------------");
                    Response.Write("the following InnerException reported:" + ex.InnerException.ToString());
                    ex = ex.InnerException;
 
                }
 
            }
 
        }
 
        Datareader.Close();
        DBConnection.Close();
    }