I saw a new marketing strategy recently: Someone tried to sign into something with my email. I didn't have an account, so they took the excuse to send me an email asking me to create an account.

This has been going on since at least 2006.

Startups will "growth hack" by buying e-mail lists and feeding them into their password recovery tools.

A certain percentage of people will then follow the links and end up creating a new account on a service they had no interest in that now has their confirmed contact information, a new user, and a plausible reason to bombard them with marketing email.