I joined Twoo a few weeks back.
I use 2 email addresses: one for family/friends, the other to join non-critical websites (i. E. Twoo).
Last week, I received some emails from my friends telling they had received invitations from Twoo in my name.
This means that the websote is cunningly scrapping all email addresses stored on your computer no matter which email account you are using.
Avoid if you want to keep your privacy.