Thanks for the reply. The only folder in the /Mail folder is V4, which contains mail files (mostly .plist) from older email addresses, circa 2017-2020. No results from /Mail/V10.
I moved from business emails to a couple personal emails a few years back, and those aren't showing.
As to why: yes, I'm being especially cautious, wanting to be sure I don't lose archived emails as I change mail servers on the same email address (new web host for that personal domain). Thus I moved them to an On My Mac folder, rather than the server-side IMAP folder where they've been living. I just wanted to know how to open them locally, outside of Mail, in case once I'm up again with my new mail server, they either don't open right in Mail (snafu with same email address and different server), or -- worst case scenario -- Mail crashes or corrupts somehow. So I wanted to see where they live and how are named/open up locally....and can't find that folder.
(Ideally, once I'm up with my new server, I can move them into the new Archives folder for my main personal email address on the IMAP server...or, I may just let these old one live separately in the On My Mac section of Mail.)
If you have input on any of that, I'd be most grateful.
(site note: I see that I can drag emails from Mail's "On My Mac" folder, into a Finder folder, where they show as .eml files with names matching Subject Lines. That's a good workaround. But I'd like to find the On My Mac folders in the Library!)
Again, many thanks.
Jim