Spam iCloud Calendar Invitations Today I've suddenly received spam calendar invitation for $19.99 Ray Ban sunglasses (never subscribed, checked, searched or visited any related site, so clearly spam) and it has other visible email accounts within the invitation.
I'm wondering if I should be worried whether my accounts been compromised or a simple email from anywhere just plops this in my calendar without review.
Questions to be answered:

What should I check/setup in order to make sure my iCloud account is safe?
How can I delete this invitation without sending a notification to the sender, so as to prevent them from knowing my email address is live?
How can I prevent these notifications in the future?

Here's an image:
Regarding how to prevent this in the future (question #3):


Log in to iCloud Calendar on a computer web browser
Authenticate if needed, then select the Calendar view
Select the Settings Gear icon ⚙ in the bottom left corner then hit Preferences...





Select Advanced


Choose the option to receive calendar invitations by email instead of allowing the server to insert them without review into your calendar:




Select Email to [youremail] instead of In-app notifications


You now get to decide and delete or process calendar spam like regular email spam, allowing you to filter out these spam calendar invitations systematically.