Mail files

Help! I've just cleaned and reinstalled my main computer system. I
saved all the files to another system before the clean and reinstall
process.

I had a lot of saved mail folders (including some CNC stuff). After
installing outlook express, I was able to move the saved inbox, sent
items and the files in the other standard folders without any
problem. However, when it comes to tranferring the old folders (I
created)and saved mails back into outlook express I can't access or
open any of them.

Anybody have any idea how to reopen all these old files?

Thanks, Smoke