I had a 40GB data of an NSF file and I wanted to convert it into PST format. I digged Google to get a proper solution where I found a manual solution from here: cybrary.it/0p3n/convert-nsf-to-pst-format-and-migrate-ibm-lotus-notes-data-to-outlook/
I took a back-up my data and tried the manual process. It consumed so much time and at the end, the process failed and I didn't get the complete NSF emails into Outlook. So I asked my friend for a solution they suggested me to use MailsDaddy NSF to PST Converter tool which is very simple to use and there is no need to have any expertise to operate the tool. I tried the tool's Personal license which I got only in $99. The tool exported all the NSF file data into Outlook PST at once and provided me 100% data of NSF file. I recommend, use this tool if you want to Lotus Notes to Outlook Migration.