A nice overview https://www.stuff.co.nz/national/115118698/how-the-national-library-preserves-new-zealands-digital-heritage of what it means to preserve historical documents in the digital online age. What happens when the legal obligations of the National Library collide with the terms and conditions of overseas-run sites hosting content posted by New Zealanders? How do you deal with private/defamatory/pornographic material? Proprietary file formats?

Some people are even donating their e-mail archives to the Library.