I use CSmtpClientMtm to send an email with attachment by following code.

TFileName dir;
TMsvId attachId;
(CSmtpClientMtm*)smtpMtm->CreateAttachmentL(attachId,dir);
dir.Append(_L("attach.txt"));
TBuf<20> file(_L("c:\\attach.txt"));
RFs fs;
fs.Connect();
fs.Replace(file,dir);
fs.Close();
smtpMtm->SaveMessageL();

It was successful on creating the file on the directory of mail outbox
like c:\system\Mail\00001001_S\b\ and sending the mail.
However, I could not see the attchment filename inside the mail
and the mail body message became unreadable when I received it.
What's wrong? some setting needed to make the attachment visible?
But there is no the interface on CSmtpClientMtm.