/// <summary>
        /// 傳送郵件
        /// </summary>
        /// <param name="fromMail">發件人郵箱</param>
        /// <param name="toMail">收件人郵箱</param>
        /// <param name="subject">主題</param>
        /// <param name="body">內容</param>
        /// <param name="clientHost">
 
設定用於 SMTP 事務的主機的名稱或 IP 地址</param>
        /// <param name="roleCode">生成授權碼</param>
        /// <returns></returns>
        public static bool SendMessage(string fromMail, string toMail, string subject, string body, string clientHost, string roleCode)
        {
            MailMessage mailMessage 
 
= new MailMessage();
            //發件人郵箱
            mailMessage.From = new MailAddress(fromMail);
            //收件人郵箱
            mailMessage.To.Add(new MailAddress(toMail));
            //主題
            mailMessage.Subject = subject;
            //內容
            mailMessage.Body = body;
            mailMessage.Sender 
 
= new MailAddress(fromMail);
            SmtpClient client = new SmtpClient();
            client.Host = clientHost;
            //使用安全加密連線。
            client.EnableSsl = true;
            //不和請求一塊傳送。
            client.UseDefaultCredentials = false;
            //驗證發件人身份(發件人的郵箱，郵箱裡的生成授權碼);
            client.Credentials = new NetworkCredential(fromMail, roleCode);
            //傳送
            try
            {
                client.Send(mailMessage);
            }
            catch (Exception ex)
            {
                return false;
            }
            return true;

        }