I just read this information in another forum - I was not aware of this feature which makes it even that much better:
| When self-destruct is activated, it wipes the content of your SD card as well. |
ALSO, the wipe also removes the Email (Message) application as well. WHY? To prevent others from reading your new emails
So, if you do decide to test this, be ready to do a reload of Message app using desktop app loader.