There are multiple software on internet that will help you to migrate lotus notes emails from NSF file format to PST file format. Here are few examples that will help you to migrate database from lotus notes nsf file format to outlook pst or few useful file extensions.
1. Softaken NSF to PST Converter
2. GainTools NSF Converter
3. Free Mailvare NSF file to PST
4. Datavare NSF to PST converter