If you have multiple orphan MSG files and you want to open it within MS Outlook then you can use for MSG to PST converter. It allows you to save several MSG files into PST format and you can import this PST file within MS Outlook. With the tool, you can keep the folder strcuture and other associated data like attachments, email formatting etc intact.

https://gallery.technet.microsoft.com/How-to-Import-MSG-Files-in-ce42e626