To Convert NSF Files into MBOX, I suggest using an automated utility for easy conversion. In this concern, I recommend NSF to MBOX Converter to export NSF into MBOX format without any difficulty. It comes with an interactive interface that lets novice users use it effectively. It can also convert multiple NSF files at one time. Moreover, you can try this utility for free by installing the trial version. It converts 50 emails free of cost.