How to find the code page ID of an Outlook message file (.msg)

Question

I want to get the Code Page ID that was used when writing an email (outlook .msg file). The property that holds this information is PidTagMessageCodepage. But I cannot find how to access it with C++.

The message file (.msg) that I am trying to read was created on a windows machine, and system locale was set to English. This email was sent to another system which system locale is Japanese (Shift-JIS Code Page). I want to identify the original code page from message file and pass it toMultiByteToWideChar()

Thank you in advance.