- For Mac users you would have to either run Outlook for Windows on your Mac (expensive and time consuming) or install an MSG viewer app, which is free or low cost in the Mac App Store.
https://apps.apple.com/us/app/msg-viewer-pro/id1019539949 4.99
https://apps.apple.com/us/app/msg-viewer-for-outlook/id973213640?mt=12 free