Cigati PST to NSF Converter tool is the most reliable tool to convert the Outlook PST files into the NSF files and also this utility converts the PST files into different file formats and various other email clients. Users can save their migrated or converted files into their personal offline storage with all kinds of attachments. This software has a demo version which provides 50 email conversions free.
Source: http://www.cigatisolutions.com/pst-to-nsf-converter/