Register After send verficaition Email On gmail Account

class
{
public string TO { get; set; }
    public string SUBJECT { get; set; }
    public string BODY { get; set; }
    public void sendmail()
    {
        MailMessage msg = new MailMessage();
        msg.From = new MailAddress(FROM);
        msg.To.Add(TO);
        msg.Subject = SUBJECT;
        msg.Body = BODY;
        msg.IsBodyHtml = true;
        SmtpClient client = new SmtpClient();
        client.Host = "smtp.gmail.com";
        client.EnableSsl = true;
        client.Credentials = new NetworkCredential();
     //   client.UseDefaultCredentials = true;
        client.Port = 587;
        client.Send(msg);
    }
}