When receiving an encrypted message, it has an attachement that can according to the flap be open/saved. However, touching these buttons does not have a noticeable effect. On a mobile device like the N900, I would not have expected such functionality in the first place (esp. not the "open" one). Seen in version 4:4.5~20100910.1175630-1maemo6.1174786 .
*** This bug has been marked as a duplicate of bug 248361 ***