The Family Educational Rights and Privacy Act (FERPA) gives registered students the right to inspect and review their educational records. If you do not waive your rights and you become a registered student at Princeton, you would have access to view recommendation letters in the future. This only applies to applicants that are offered admission, accept our offer, and become students. Applicants who do not become students will not be able to view recommendation letters under any circumstances.
The email that your recommender will receive from Princeton indicates if FERPA rights have been waived or not, and this may influence what the recommender writes in the reference.