Nearly every day, I get 4 copies of a bunch of spam trying to sell me Shopify inventory management, Shopify store marketing, Shopify product feed management, Shopify shipping services, etc.
Why Shopify? Because there's a script tag on my sites with the word "shopify" in it. I don't run any Shopify stores.
Why 4 copies of every mail? Because I have 4 sites with that tag.
BuiltWith sells my contact info in their list of "Shopify websites", which these people toss into MailChimp and spam away, despite the fact that unsolicited mailings are a ToS violation there and everywhere else. I know BuiltWith is the source since one of them named their MailChimp list "BuiltWith Shopify US".
It's a brilliantly simple and profitable site that I wish I had come up with, but the fact that the business model they ended up at is basically "harvested e-mail vendor for spam" kinda sucks.