An old open-source tool called hypermail may be what you're looking for. It parses mbox files and produces HTML pages with the emails sorted by thread, author, subject, date, etc. http://hypermail-project.org/
The expert colleague actually got the *wrong* answer for xy_common. To me, that is the most interesting part of this experiment! What does that tell us? Maybe the "experts" could learn a thing or two from the novices, e.g., slow down a bit and verify results
If you just need debugging, try cgdb. It's very lightweight.
The OST file format is pretty much identical to PST.