Re: what I mean
I think you understand it correctly.
What I meant was: copy inbox1.dbx AAAMessagebox.dbx
That's the command line command to copy inbox1.dbx to AAAMessagebox.dbx and overwrite it if it already existed. Copy a file over another file so to say, replacing it.
In the GUI offered by Windows Explorer it's a 3-step procedure:
1. Delete AAAMessagebox.dbx
2. Copy (ctrl-c, ctrl-v) inbox1.dbx to Copy of inbox1.dbx
3. Rename Copy of inbox1.dbx to AAAMessagebox.dbx
And then, if you run OE again, your AAAMessagebox isn't empty anymore, but litterally is the old inbox1.