The Notes Storage Facility (NSF) database file is used by (IBM) Lotus Notes and Domino to store different kinds of objects like e-mail, appointments, and documents, but also application forms and views. Vaultastic can ingest these files, but after conversion to directly supported file formats like PST/EML or MBOX. There are commercially available NSF to PST converters which can get this done.
NSF to PST
PST To NSF