NSF files act as databases for IBM Notes. They pack emails, contacts, and tasks into one bundle. IBM locks down the format, full of hidden links and custom setups. You cannot simply open an NSF file in Outlook and save it as a PST. The structures don't match up. Notes uses its own way to index items, like a secret code that only it reads. https://theomnibuzz.com/how-to-convert-nsf-to-pst-without-lotus-notes-