Email Migration from corrupted MSN database

I have a client who had a system crash. I rebuilt his machine, but he had a whole bunch of saved emails in his MSN email client program. Unfortunately, copying the application data folder back to the new install resulted in MSN vomiting up most of its major internal organs...

So I've dug through the files and discovered that all of his emails are stored as individual files in ASCII. So far so good. But any hint of his organization folders is stored somewhere that I can't find. (Maybe I'm blind.) Furthermore, it seems that MSN never purged any of the messages he deleted, so there's about 40 GB of junk to sort through.

I'm looking for a program capable of crawling through an arbitrary list of message files, properly formatting HTML messages and displaying any included pictures or other attachments, and then saving the messages he wishes to keep into an easily portable mailbox format. I don't really care if it does it all itself or uses helper programs, or even what OS it runs on, just so long as it works.

Unfortunately, if any such program exists, it does not seem to be well advertised. I'm guessing there are probably some mail clients that could do it, but I haven't found any where it's on their list of features, and I have neither the time, nor the patience to download and test them all individually.

Are there any recommendations for what to try?