private void btnGuiMail_Click(object sender, EventArgs e)
        {
            if (XtraMessageBox.Show("Bạn muốn gửi mail ?", "Câu hỏi", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                List <string> vs = new List <string>();
                if ((txtFileDinhKem.EditValue ?? string.Empty) != string.Empty)
                {
                    vs = txtFileDinhKem.EditValue.ToString().Split(',').ToList();
                }

                O_CAUHINHSMTP cauHinhSMTPO = new D_CAUHINHSMTP().DuLieu();
                O_MAUEMAIL    ma           = new D_MAUEMAIL().DuLieu()[0];

                SmtpClient client = new SmtpClient();
                client.Port                  = cauHinhSMTPO.Port;
                client.Host                  = cauHinhSMTPO.Host;
                client.EnableSsl             = cauHinhSMTPO.SSL;
                client.Timeout               = 10000;
                client.DeliveryMethod        = SmtpDeliveryMethod.Network;
                client.UseDefaultCredentials = false;
                client.Credentials           = new System.Net.NetworkCredential("*****@*****.**", "time0326");

                if (txtTen.Text.Length > 5)
                {
                    MailMessage mm = new MailMessage();
                    mm.From         = new MailAddress("*****@*****.**", "Thành Hoàng");
                    mm.BodyEncoding = UTF8Encoding.UTF8;
                    mm.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
                    mm.IsBodyHtml = true;
                    RichEditMailMessageExporter exporter = new RichEditMailMessageExporter(txtMauEmail, mm);
                    exporter.Export();
                    mm.To.Add(new MailAddress(txtTen.Text));
                    mm.Subject = txtTieuDe.Text;

                    foreach (string g in vs)
                    {
                        if (g.Count() > 0)
                        {
                            mm.Attachments.Add(new Attachment(g));
                        }
                    }
                    try
                    {
                        client.Send(mm);
                        XuLyGiaoDien.Alert("Gửi mail thành công", Form_Alert.enmType.Success);
                    }
                    catch (Exception ex) { XuLyGiaoDien.Alert(ex.Message, Form_Alert.enmType.Error); }
                }
            }
        }