The file("c:\\filename.txt" ) i used for attachment cannot delete until the application terminated..

Is there anyway i can delete it?  Is it suppose to work this way???
Thanks in advance..


    CDO::IBodyPart* pIBodyPart = NULL;
    if ( SUCCEEDED(  m_pIMessage->AddAttachment( L"c:\\filename.txt",L"",L"",&pIBodyPart )
    {
                hr = pIBodyPart->put_ContentMediaType( _bstr_t( "text/plain" ) );
                std::string  strDisposition ="attachment;filename=" ;
                strDisposition += SZ_FILTERFILE ;
                {
                    Field*  pField = NULL;
                    Fields* pFields = NULL;
                    hr = pIBodyPart->get_Fields( &pFields );
                    // Disposition.
                    hr = pFields->get_Item( _variant_t( "urn:schemas:mailheader:content-disposition" ), &pField );
                    _bstr_t bstrDisposition( strDisposition.c_str() );
                    hr = pField->put_Value( _variant_t( bstrDisposition ) );
                    pField->Release();
                    pField= NULL;
                    hr = pFields->Update();
                    pFields->Release();
                  
                }
}