I received an email about threads and Mastadon a bit ago. The thing is I deleted my Mastadon account a hot minute after I created it. The email has no way to unsubscribe from it 
I would like to be comforted that I’m overthinking this. My Mastadon account was a couple of years ago in both creation and deletion. It’s incredibly disconcerting.
Only looking at the collapsed post I can see why they might think it was about Threads.