> There've been many rumors over the years that Unroll.me sells information about the emails it scans.
It's not just rumors, it's stated clearly (if in softened terms) on the site now[1]. Although it wasn't for the first few years, as their original monetization model wasn't based on it.
The big stink about it was that they shifted to that model silently. The original founder only monetized it in a straightforward manner via ads in the app. Then it was sold to Slice/Rakuten, and they silently incorporated it as part of Slice's consumer intelligence data, along with data from other subsidiaries they bought such as Ebates.
Small aside: Rakuten also has a major stake in Acorn[2]. Acorn uses Plaid to verify bank account information for payouts. Plaid[3] is incredibly handy from a consumer experience, but the implications are scary from an "alternative use" perspective. Once connected, there are several handy Plaid products[4] which can make use of that authorization, above and beyond just confirming account ownership. Such as continuously siphoning off transaction level records or keeping tabs on income and employment fluctuations[5].
Not that Rakuten is leveraging their stake in Acorn to access Acorn's bank authorization for those ulterior uses. But it's food for thought on what possibilities exist.
> I think it's even more telling of the "trade data for service" paradigm that people continue to use the service even after finding out
I agree wholeheartedly with this assessment. Although I wonder how much their subscriber growth rate changed after their alternative data use came to light.
[1] https://unroll.me/your-data
[2] https://techcrunch.com/2016/04/21/paypal-invests-30-million-...
[3] https://plaid.com/
[4] https://plaid.com/products/
[5] https://plaid.com/products/income