INFO: Save Message to MSG Compound File

    #define INITGUID
    #include <objbase.h>

    #define USES_IID_IMessage

    #include <mapix.h>
    #include <mapitags.h>
    #include <mapidefs.h>
    #include <mapiutil.h>
    #include <mapiguid.h>
    #include <imessage.h>

    // {00020D0B-0000-0000-C000-000000000046}
    DEFINE_GUID(CLSID_MailMessage,
    0x00020D0B,
    0x0000, 0x0000, 0xC0, 0x00, 0x0, 0x00, 0x0, 0x00, 0x00, 0x46);

    HRESULT SaveToMSG ( LPMESSAGE pMessage )
    {
        HRESULT hRes = S_OK;
        LPSPropValue pSubject = NULL;
        LPSTORAGE pStorage = NULL;
        LPMSGSESS pMsgSession =  NULL;
        LPMESSAGE pIMsg = NULL;
        SizedSPropTagArray ( 7, excludeTags );
        char szPath[_MAX_PATH];
        char strAttachmentFile[_MAX_PATH];
        LPWSTR lpWideCharStr = NULL;
        ULONG cbStrSize = 0L;

        // create the file name in the directory where "TMP" is defined
        // with subject as the filename and ".msg" extension.

        // get temp file directory
        GetTempPath(_MAX_PATH, szPath);

        // get subject line of message to copy. This will be used as the
        // new file name.
        HrGetOneProp( pMessage, PR_SUBJECT, &pSubject );

        // fuse path, subject, and suffix into one string
        strcpy ( strAttachmentFile, szPath );
        strcat ( strAttachmentFile, pSubject->Value.lpszA  );
        strcat ( strAttachmentFile, ".msg");

        // get memory allocation function
        LPMALLOC pMalloc = MAPIGetDefaultMalloc();

        // Convert new file name to WideChar
        cbStrSize = MultiByteToWideChar (CP_ACP,
                                         MB_PRECOMPOSED,
                                         strAttachmentFile,
                                         -1, lpWideCharStr, 0);

        MAPIAllocateBuffer ( cbStrSize * sizeof(WCHAR),
                                (LPVOID *)&lpWideCharStr );

        MultiByteToWideChar (CP_ACP,
                             MB_PRECOMPOSED,
                             strAttachmentFile,
                             -1, lpWideCharStr, cbStrSize );

        // create compound file
        hRes = ::StgCreateDocfile(lpWideCharStr,
                                  STGM_READWRITE |
                                  STGM_TRANSACTED |
                                  STGM_CREATE, 0, &pStorage);

        // Open an IMessage session.
        hRes = ::OpenIMsgSession(pMalloc, 0, &pMsgSession);

        // Open an IMessage interface on an IStorage object
        hRes = ::OpenIMsgOnIStg(pMsgSession,
                                MAPIAllocateBuffer,
                                MAPIAllocateMore,
                                MAPIFreeBuffer,
                                pMalloc,
                                NULL,
                                pStorage,
                                NULL, 0, 0, &pIMsg);

        // write the CLSID to the IStorage instance - pStorage. This will
        // only work with clients that support this compound document type
        // as the storage medium. If the client does not support
        // CLSID_MailMessage as the compound document, you will have to use
        // the CLSID that it does support.
        hRes = WriteClassStg(pStorage, CLSID_MailMessage );

        // Specify properties to exclude in the copy operation. These are
        // the properties that Exchange excludes to save bits and time.
        // Should not be necessary to exclude these, but speeds the process
        // when a lot of messages are being copied.
        excludeTags.cValues = 7;
        excludeTags.aulPropTag[0] = PR_ACCESS;
        excludeTags.aulPropTag[1] = PR_BODY;
        excludeTags.aulPropTag[2] = PR_RTF_SYNC_BODY_COUNT;
        excludeTags.aulPropTag[3] = PR_RTF_SYNC_BODY_CRC;
        excludeTags.aulPropTag[4] = PR_RTF_SYNC_BODY_TAG;
        excludeTags.aulPropTag[5] = PR_RTF_SYNC_PREFIX_COUNT;
        excludeTags.aulPropTag[6] = PR_RTF_SYNC_TRAILING_COUNT;

        // copy message properties to IMessage object opened on top of
        // IStorage.
        hRes = pMessage->CopyTo(0, NULL,
                                (LPSPropTagArray)&excludeTags,
                                NULL, NULL,
                                (LPIID)&IID_IMessage,
                                pIMsg, 0, NULL );

        // save changes to IMessage object.
        pIMsg -> SaveChanges ( KEEP_OPEN_READWRITE );

        // save changes in storage of new doc file
        hRes = pStorage -> Commit(STGC_DEFAULT);

        // free objects and clean up memory
        MAPIFreeBuffer ( lpWideCharStr );
        pStorage->Release();
        pIMsg->Release();
        CloseIMsgSession ( pMsgSession );

        pStorage = NULL;
        pIMsg = NULL;
        pMsgSession = NULL;
        lpWideCharStr = NULL;

        return hRes;
    }