How do companies like Superhuman get all your social info?

[caelinsutch]

I've always wondered how platforms like Superhuman can aggregate a ton of data on someone, like their Linkedin or Twitter, based purely off email. I saw that the founder previously founded Rapportive which did this as a service.

[verdverm]

While everyone complains about Google, the secondary data market is far worse and remains largely in the shadows.