When I have the same issue then my friend suggested I try this tool and I tried this tool and got a great result. For this purpose, I would like to suggest
NSF to PST Converter Software. It allows importing single as well as multiple database items such as contacts, notes, messages, emails, journal items, tasks, to-do lists, etc. The software is capable to export NSF files into different file formats like PST, MSG, MBOX, EMLX, and others.