EML to MSG conversion fails when IStorage is used

StackOverflow https://stackoverflow.com/questions/16995450

  •  31-05-2022
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Question

I am trying to convert EML in to MSG file. I create mapi object IMessage on IStorage object; Assign class-id CLSID_Message to IStorage object; Parse EML file, read properties and assign them to mapi IMessage object; Called Save() on mapi IMessage object; Called Commit() on IStorage object; The generated MSG file was not readable by Outlook. So I tried another method, as briefed below.

Created 2nd IMessage object on IStorage; Called IMessage::CopyTo() on 1st IMessage object, to transfer data to 2nd IMessage that is hosted on IStorage object; Generated MSG file was again unreadable by OutLook.

If I create IMessage object inside PST then the generated MSG file is readable by OutLook. I think there is something happening when I create IMessage on IStorage. I am able to read PR_SUBJECT from the IMessage object, so EML->MAPI conversion has taken place(this code has worked for years).

Here the code 

void EmlToMapiTest()
{
    const wchar_t* msgFileName = L"C:\\M1.msg";
    const wchar_t* emlFileName = L"C:\\E1.eml";
    IStorage*  pIStorage = 0;
    IMessage*  pIMessage = 0;
    DWORD gfMode = STGM_CREATE | STGM_TRANSACTED | STGM_READWRITE;
    STGOPTIONS sOptions = {0}; 
    sOptions.usVersion = 1;
    sOptions.ulSectorSize = 4096;
    IMalloc* lpMalloc = MAPIGetDefaultMalloc();
    HRESULT hr = ::StgCreateStorageEx(msgFileName,
    gfMode, STGFMT_DOCFILE, 0, &sOptions, 0, IID_IStorage,
    (void**)&pIStorage); 

    WriteClassStg(pIStorage, CLSID_IMessage);

    hr = OpenIMsgOnIStg(NULL ,
                Mapi::MAPIAllocateBuffer,
                Mapi::MAPIAllocateMore,
                Mapi::MAPIFreeBuffer,
                lpMalloc,
                NULL,
                pIStorage,
                NULL, 0, MAPI_UNICODE, &pIMessage);

    _bstr_t bstrEMlFile = emlFileName;
    DoConvert(bstrEMlFile,pIMessage); //Our own Mime <-> Mapi library

    pIMessage->SaveChanges(KEEP_OPEN_READWRITE);
    pIStorage->Commit(STGC_DEFAULT);

    pIMessage->Release();
    pIStorage->Release();
}

Please let me know if any of you have experience with this stuff.

Thank you

Was it helpful?

Solution

Try to open the MSG file in OutlookSpy (I am its author) - click OpenIMsgOnIStg button. Are any properties missing compared to a good message?

Then try to use IConverterSession to perform the conversion.

What is the exact error displayed by Outlook? Make sure you correctly set the PR_MESSAGE_CLASS property.

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