Thanks for the advice and quick response.  I followed your instructions and added the GRP files to one mailbox.  I do not see the emails in the mailbox right now and I've waited about an hour or so.  Do I have to do anything further?

You're very welcome! Thats an interesting result! You stopped the service correct? (Click Start, type services.msc, stop the SmarterMail system service.) You should only need to delete the mailbox.cfg in that folder, then start the SmarterMail system service once again. Let me know how it goes :)

Actually, I thought that the deletion of the mailbox.cfg was optional, with the only caveat is that the unread counts would be off if you didn't do that.  I stopped the service again and deleted the mailbox.cfg and I see the emails now.  
A follow up question would be that if I restored the folder structures and removed the root.cfg, would that repopulate the folder structure for the mailbox or am I reaching too far?

Glad to hear that worked! Unfortunately the mailbox.cfg must be deleted to reindex the contents of the folders, so thats why I usually recommend restoring into another folder to be safe. On your follow up question, yes, it should. Deleting the root.cfg should cause SM to reindex the folders and their contents, but we also store folder titles and IDs in a folders.json file in newer versions so this may not be sufficient. I recommend trying this first with an account you're not worried about playing with, then go from there once you have a good process. Glad you got it working! Have a great weekend.