Microsoft doesn't provides any free utility for NSF to PST conversion, but there are few manual methods for conversion. In manual methods there is no need any third party tool. I would like to suggest you take a help of this blog post: migrateemails.com/2016/01/22/export-lotus-notes-email-to-microsoft-outlook/ through this blog you can effectively convert all NSF file emails to Outlook PST format without losing any data.