Thanks for this informative post. I tweeted such an issue a few days ago. I had problem with one of my payment account and I tweeted this issue. Than I received a phishing email. The point is that how scammers know my email that just twitter know?
Even people in companies who have authority to access sensitive data are part of this.
Yes, you are right. big companies can sell our e-mail information for money. We do not know who our information is.