But better yet! Yesterday (11-29) Sean Gallagher of Ars Technica posted a permanent solution to Calendar spam rat attacks that works the charm. It shoves off spam 'invitations' (infestations) into the Mail application instead, where the crapulent assaults will be forced through your spam filtration system, killing them dead.
√ Spam rat exterminated.
How to stop the wave of Apple Calendar invite spam
Deleting them just encourages them—and confirms your address is live.
Sean Gallagher, Ars Technica, 2016-11-28
Here is my slightly simplified set of instructions. Note that this must be performed on a desktop/laptop computer. It will not work using iOS!
1) Sign in (log in) to your iCloud account at:
2) Click on the Calendar icon.
3) When your Calendar page is loaded, look down at the bottom left for the gear symbol. Click on it and choose 'Preferences'.
4) In the Preferences sub-window, click on the 'Advanced' tab.
5) In the bottom section of the 'Advanced' window, labeled 'Invitations', you'll see the default radio button setting is 'In-app notifications'. Click instead 'Email to ...' your iCloud email address. (Ignore 'Use this option if...).
6) Click 'Save' in the bottom right.
No more 'invitation' infestations into your Calendar. But note! Any legitimate Calendar invitations will also be sent to your email account. Therefore, be careful when perusing your email to watch for invitations you'd like to accept. In Mail you can choose to have them added to your Calendar.
When you receive spam rat 'invitations' in Mail you can simply mark them as 'Junk'. More garbage from the same spam rats should in future be flung into your 'Junk' without your having to ask.
Reporting Calendar 'Invitation' Spam:
I had a chat with tech support over at SpamCop.net about Calendar 'invitation' spam. They kindly declined to recode their spam reporting website software to accept this new spam variety and instead referred me to another organization that might take up the challenge. But the fix Sean Gallagher provided solves the problem. I can in future toss off 'invitation' spam to SpamCop directly from Mail.
Remaining problem, iCloud Photo Sharing spam:
Sadly, there is no similar preference fix to stop iCloud Photo Sharing spam. That one is Apple's burden to solve.