public static SmtpClient GetSmtpClient()
    {
      SmtpClient smtp = new SmtpClient("smtp.server.com");
      if (WebConfigurationVariables.SMTPUseAuth)
      {
        smtp.Credentials = new NetworkCredential("username", "password");
      }
      return smtp;
    }
 
    protected void ButtonSubmit_Click(object sender, EventArgs e)
    {
      if (IsValid)
      {
        List<string> Sql = new List<string>();
        Sql.Add("Message:");
        Sql.Add(TextBoxMessage.Text);
 
        try
        {
          SmtpClient smtp = GetSmtpClient();
          using (MailMessage msg = new MailMessage())
          {
            msg.From = new MailAddress("feedback@______.com", "Online Feedback");
            msg.Sender = new MailAddress("feedback@______.com", "Online Feedback");
            msg.To.Add(new MailAddress(WebConfigurationVariables.FeedbackEmail));
            msg.Subject = "Feedback from www.______.com";
            msg.Body = "your message body here";
            msg.IsBodyHtml = false;
            msg.ReplyTo = new MailAddress("noreply@______", "No Reply");
            smtp.Send(msg);
          }
        }
        catch (Exception ex)
        {
          Log.Exception(ex, Request);
        }
      }
    }