One of our staff members has lost his mailbox but luckily has a dump of his email in mbox format. I need to somehow get all the messages inside the mbox file and squirt them
I don't know any parser, but mbox is really a very simple format. A new email begins on lines starting with "From " (From+Space) and an empty line is attached to the end of each mail. Should there be any occurence of "From " at the beginning of a line in the email itself, this is quoted out (by prepending a '>').
Also see Wikipedia's entry on the topic.