To convert PST to MSG easily, I recommend using a reliable utility like PST to MSG Converter. This PST to MSG Tool is highly supportable with all versions of Windows OS. It helps to convert PST file into MSG format with all items such as mailboxes, contacts, notes, tasks, etc. The best thing about this software is that it does not affect the folder hierarchy during conversion. It also comes with a free test version which converts 50 items for free. https://www.convertertools.org/pst-to-msg/