Moved to Forum: Original Link
From the email:
"You can now earn twice as much free space by inviting your friends!
For each friend that installs Dropbox, you’ll both get 500 MB of free space. You can earn up to 16 GB.
P.S. Already invited a bunch of people? Don't worry! You'll get credited for all of them."
Not sure if the friend just has to sign up to Dropbox or actually install their software.
I wonder if this stacks with the linking of edu email accounts. ie. if linked to an edu email, every referral gives 1 GB of space?
Not really a bargain, probably belongs in the forums as it's permanent