Subject: Not sure about on MAC but it’s worth a try …
I guess I’m coming to this a bit late, however, I’m running Windows and can select a message and then drag it to a filesystem folder in my File Explorer UI:
If you do the same, you’ll get this warning, just press [OK]
The email will then appear on your OS’ filesystem as a file with a .eml extension.
NOTE: I’m currently using the Basic, not Standard, client so I’m not sure if it’s possible to select more than one message and drag it over. With Basic I only seem to be able to do one at a time.