iPhone Calendar event invitation notification spam

It's Thanksgiving day today and for some reason, I got a notification from my iPhone calendar about a Michael Kors sale.

I hate shopping on Black Friday. It's just simply not worth it to duke it out with other shoppers for a measly $50 discount. So seeing this notifcation on my calendar about a sale is odd.

Looking at the calendar entry, someone has figured out how to add entry to my calendar by sending email to my iCloud account. So how did this person found my iCloud email when it is not my primary email? It seems like iCloud was hacked.

But my biggest question is, how did this event manage to be added on my Calendar and pushed an alert. This is a new clever way to spam people. Apple has to fix this.

UPDATE FIX: 
Here's a fix from the comment posted by Cryon. Apparently, invites are being sent directly to the calendar app. You have to disable it so it is sent to your email. Then from your email, you can mark it as spam.

1. Go to https://www.icloud.com/#calendar
2. Go to Preference on lower left corner.
3. Click Advanced.
4. Then select "Receive calendar invitations by email instead of straight into your calendar app".