This script was written by the person who runs this website: http://www.broobles.com/
It did not work with recent Ruby versions, and did not have an Arch Linux package. So I am semi-forking it here. They are always welcome to unfork it and take the credit. :)
It can handle files that end in EML or MAI (aka RFC 822) such as the ones stored by Mail Enable. It turns these into mbox files.