Your Dropbox space is not enough? Don’t worry. If you have an iOS device, you can get 1 additional GB for free.
If you visit https://www.dropbox.com/getspace you might notice that there is an offer for 1GB of storage by linking your Dropbox account with Mailbox.
All you need to do is download the Mailbox app on your iOS device and link your Dropbox account. Once you’ve done that, go to the link above and the bonus will appear in your account.”
Instructions (requires an iOS device):
1. Install Mailbox [apple.com] app
2. Log into gmail account (doesn’t seem to be a way to bypass this) via Mailbox app
3. Link your Dropbox account
4. Verify that 1GB was added by logging into your Dropbox account
You can unlink/delete the app and your space will remain.