在win2k繁體操作系統中，Jmail發送附件亂碼現象

1.後台代碼：
private void btn_send_Click(object sender, System.EventArgs e)
{   //建立發郵件對象
jmail.MessageClass oJmailMessage= new jmail.MessageClass();
oJmailMessage.Charset="Big5";
oJmailMessage.Encoding="BASE64";
oJmailMessage.ContentType="text/html";
oJmailMessage.ISOEncodeHeaders=false;
oJmailMessage.Priority=Convert.ToByte(1); oJmailMessage.From=TxtEmail.Text.Trim();
oJmailMessage.FromName=TxtName.Text.Trim();
oJmailMessage.Subject=txtSubject.Text.Trim();
oJmailMessage.MailServerUserName=TxtSmtUser.Text.Trim();
oJmailMessage.MailServerPassWord=TxtSmtPwd.Text.Trim();
oJmailMessage.AddRecipient(txtReciver.Text.Trim(),"",""); if(""!=upFile.PostedFile.FileName)
{
string attpath=upFile.PostedFile.FileName;
oJmailMessage.AddAttachment(@attpath,true,attpath.Substring(attpath.LastIndexOf(".")+1,3));
} oJmailMessage.Body=TxtContent.Text.Trim();
if(oJmailMessage.Send(TxtSmtServer.Text.Trim(),false))
{
Response.Write("cheng gong le"); }
else
{
                 Response.Write("shi bai le");
} oJmailMessage=null;

}
2.outlook收到郵件的亂碼：
This is a multipart message in MIME format. ----NEXT_BM_CCFD699F44AA42CFBE12D3E2AD524BC1 Content-Type: text/plain; charset="Big5" Content-Transfer-Encoding: Quoted-Printable mail test ----NEXT_BM_CCFD699F44AA42CFBE12D3E2AD524BC1 Content-Type: rar; name="rrr.rar" Content-Transfer-Encoding: BASE64 Content-Description: rrr.rar Content-Disposition: inline; filename="rrr.rar" Content-ID: <2228AEE049194BF681F856540C50D612> UmFyIRoHAM+QcwAADQAAAAAAAADCwHQgkjEAAAAAAAAAAAACAAAAAH1JGDMd MA8AIAAAAHJyclxlZWUudHh0AAHACQDACl504JIsAAAAAAAAAAAAAgAAAACD SRgzFDAHABAAAABycnIAAcABALCUNXfEPXsAQAcA ----NEXT_BM_CCFD699F44AA42CFBE12D3E2AD524BC1--