Yes Drop box is one of them cloud computing thingies so I would not be uploading your social security details to it.
For all this type of stuff I use a dummy email address ( yahoo, gmail etc ) to join drop box ( or most other forums including this one ).
Once the drop box acount i opened you never look at the email account I used to open it with.
This stops your computer from being hacked and prevents your in box being filled with spam .
I use a yahoo email address and once every couple of months I look at it with my web browser and delete everything in the mail box.
