asp.net 邮件发送，使用外部stmp服务器

public void MailSend(string[] mails)
{ 

  try
        {
            MailMessage message = new MailMessage();
            foreach (string mail in mails)
            {
                message.To.Add(mail);//收件人地址 
            }

            if (txtCC.Text != "")
            {
                string[] cc = txtCC.Text.Split(';');
                foreach (string str in cc)
                {
                    message.CC.Add(str);//抄送的地址
                }
            }
            message.From = new MailAddress("ceshi@yeah.net", "管理员", System.Text.Encoding.UTF8);
            message.Subject =txtTitle.Text.Trim();  //邮件主题
            message.IsBodyHtml = true;//是否为html格式的邮件
            message.Body = FreeTextBox1.Text;//邮件的内容

            string smtp = "smtp.yeah.net";//因为我用的是163的邮箱，所以这里用到的是用163的
            SmtpClient sc = new SmtpClient(smtp);//发送邮件用到的smtp主机(用不同的邮箱，stmp定义则不同)
            string email = "email";//ConfigurationManager.AppSettings["email"];
            string pwd = "pwds";//ConfigurationManager.AppSettings["email_pwd"];
            sc.Credentials = new System.Net.NetworkCredential(email,pwd);//邮箱账号与密码 
            sc.Send(message);   //发送邮件
        }
        catch (SmtpException se)
        {
            Response.Write("<script>alert('"+se.ToString()+"');</script>");
        }

}