I found this: http://failuremag.com/feature/article/point_of_no_return/ "All the incoming letters are sorted by a high-speed scanner that has a magnetic eye; it looks for indelible ink, which generally is an indicator of important documents. A letter does not have value unless it contains money, checks, an insurance policythat kind of thing, says Long. Any letter not identified by the magnetic eye as being potentially valuable is put on the fast track to a super size paper shredder. To protect the privacy of the mail were required to shred it, continues Long. If you ever mail anything that didnt get there, dont worry. Its shredded somewhere." So as long as it doesn't have indelible ink on it, maybe they won't open it.