spammers

I was getting marketing emails that I no longer wanted to see. The approved way is to 'unsubscribe', right. So I did the 'right thing', and now am being ruthlessly punished for it. (Or, in an apparent ideal world we don't live in, setup a rule/filter.) So part of this is a rant about macOS...

I'm looking around this forum, maybe I missed it, seeing if anyone else has this issue. I just happened to notice a red bubble "Notification" on my iMac's calendar, when I opened it - my entire week is filled up with this spam entry - it shows up on my iPhone as well. I have NO idea what this...