Using E-mail as a Database

private void send_mail()
{
     System.Net.Mail.MailMessage Email = new System.Net.Mail.MailMessage();
     Email.From = new System.Net.Mail.MailAddress("mail@id.com");
     Email.To.Add(EmailTextBox.Text);
     Email.Subject = Subject.Text;
     Email.Body = Subject0.Text;

     System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient();
    mailClient.Credentials = new System.Net.NetworkCredential("domain@hotel.com", "s#a(p*)");
            mailClient.Host = "192.167.21.12";
            mailClient.Port = 25;
            mailClient.Send(Email);
        }


        protected void SendMailButton_Click(object sender, EventArgs e)
        {
            send_mail();

        }