asp.net 群发邮件...

namespace Mail
{
    public static class mail
    {
        public static void GetparaBySendmail(string mailaddress,string title,string file ,string content,string fromname,string pwd)
        {
            MailMessage mails = new MailMessage(); //创建邮件类
            string fileone;
            mails.From = new MailAddress(fromname, fromname, System.Text.Encoding.UTF8);//说明指定发件人的信息 收件的地址
            mails.Subject = title;
            fileone=file;
            if (file!=String.Empty) //判断文件是否为空
            {
                AlternateView avfile = new AlternateView(fileone);

                mails.AlternateViews.Add(avfile);
            }
            mails.BodyEncoding = System.Text.Encoding.UTF8;//文件编码
            mails.IsBodyHtml = true;//是否为HTML格式
            mails.Body = content; //发送的内容

            mails.Priority = MailPriority.High;//优先级
            SmtpClient smtp = new SmtpClient(); //发送邮件的协议
            smtp.UseDefaultCredentials=true;
            smtp.Credentials = new System.Net.NetworkCredential(fromname, pwd);//发送人的邮箱
            string host = fromname.Substring(fromname.LastIndexOf("@")+1);
            smtp.Host ="smtp."+ host;
            string[] maillist= mailaddress.Split(';');
            for (int i = 0; i < maillist.Length; i++)
            {
                mails.To.Add(maillist[i]);//收件人的邮箱
            }
           
            try
            {
                smtp.EnableSsl = true;//ssl加密
                //smtp.Timeout = 1200;
                smtp.Send(mails);
                HttpContext.Current.Response.Write(" <script>alert('发送成功'); </script>");

            }
            catch (Exception e)
            {
               
                HttpContext.Current.Response.Write(" <script>alert('"+e.Message+"'); </script>");
            }
        }
    }
}