Also: https://www.reciprocity.io/ https://www.reciprocity.io/ Once in college I got an email from (I think) ecrush.com, saying "someone has a crush on you", an

Also: https://www.reciprocity.io/ https://www.reciprocity.io/ Once in college I got an email from (I think) ecrush.com, saying "someone has a crush on you", and on the site you could enter email addresses of people you had crushes on and it would spam them that same thing, anonymous until there was a match. (Personally, I suspect it was bootstrapping by sending fake initial "someone has a crush on you" emails to scraped emails, but I didn't dig in too deep.)