System.Net.Mail 发送邮件 遇到有关问题

        private void SendMail()        {            MailHelper mh = new MailHelper();            mh.To = "xxx@xx.com";            mh.CC = "xxx@xx.com";            mh.BCC = "xxx@xx.com";            mh.Subject = string.Format(CommonStatic.MAIL_SUBJECT, DateTime.Now.ToString("yyyyMMdd")).ToString();            ArrayList file_name = new ArrayList();            file_name.Add(string.Format(CommonStatic.EXCEL_NAME_ONE, DateTime.Now.ToString("yyyyMMdd")) + CommonStatic.EXCEL_NAME_END);            file_name.Add(string.Format(CommonStatic.EXCEL_NAME_TWO, DateTime.Now.ToString("yyyyMMdd")) + CommonStatic.EXCEL_NAME_END);            mh.Attachments = file_name;            mh.SendEmail(true);        }

            MailMessage msgMail = new MailMessage();            msgMail.From = new MailAddress(m_from);            msgMail.To.Add(this.m_to);            if (this.cc.Length > 0)            {                msgMail.CC.Add(this.cc);            }            if (this.bcc.Length > 0)            {                msgMail.Bcc.Add(this.bcc);            }            msgMail.Subject = m_subject;            msgMail.IsBodyHtml = m_IsBodyHtml;            if (m_Attachments != null)            {                for (int i = 0; i < m_Attachments.Count; i++)                {                    System.Net.Mail.Attachment mailAttachment = new System.Net.Mail.Attachment(m_Attachments[i].ToString());                    msgMail.Attachments.Add(mailAttachment);                }            }            msgMail.Body = m_body;            msgMail.BodyEncoding = m_MailEncoding;            msgMail.SubjectEncoding = m_MailEncoding;            if (verify)            {                msgMail.Headers.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1"); //basic authentication                msgMail.Headers.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", m_smtpUserName); //set your username here                msgMail.Headers.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", m_smtpPassword); //set your password here            }            SmtpClient smtp = new SmtpClient(m_smtpServer); //smtp邮件服务器            smtp.Send(msgMail);            msgMail.Dispose();