Superdrug and their point card shite.
I was badgered at the till to get one of these, with the promise that I would only get occasional emails with offers and promised "Oh we definitely won't spam you or anything like that!" (with tinkly little laugh).
They instantly started spamming me with multiple emails, before I'd even left the shop, and kept it up over the next few weeks.
I unsubscribed, as I'm sure any sane person would. What did that achieve, then?