No valid mbox files were found - Mail archive import

This is resolved - But I thought I post the information about the resolution for the next person who runs into this.

These files were exported (as a way of archiving them) FROM MacMail a couple of years ago. They were saved as mbox folders.

When I attempted to import the folders into MacMail, I was presented with a screen offering 2 options.

Import Data from:

1. Apple Mail
2. Files in mbox format.

Since these were in mbox format, I selected that method. But apparently if the folders were originally from MacMail, even though they were saved AS mbox folders, the correct selection is "Apple Mail". The instructions around this are a bit confusing in that the inference is that the Apple Mail selection is only for importing mail from ANOTHER Mac.

At any rate - when I selected "Apple Mail" it worked perfectly and I now have my old messages back. Hopefully this wil save the next person some trouble.

Jeff - I've read that, thanks. I believe my issue is that these mbox files are from an earlier version of OSX. This is mail that I opted to expert as mbox files as an archive rather than pull over as part of a machine migration - probably a couple of machines ago. They are clearly mbox files (as you can see below) and they appear to have quite a lot of content.

For instance, the inbox.mbox folder has an infor.plist file and a subfolder with a very long alphanumeric name. Nested inside that folder is another folder named Data and nested inside that are 12 folders named 0 through 9 and then one named Messages and another named Attachments. When I try to import inbox.mbox (or any other .mbox folder I get the error message. (picture below - sorry the pictures are in reverse order of my description)