EMLX to PST conversion requires many unnecessary steps that need to be performed manually. If you want your Mail data to be moved to Outlook PST files, there’s a more suitable way to do that than tinkering with raw files like EMLX.
How to Convert OST to PST? You can try OST Extractor Pro. An ultimate tool that it has multiple output option and works both Windows and Mac.
Here is features & FAQ of OST Extractor Pro that you need to know.
What is the best ost recovery tool and how to use it?