A new kind of spamming technique relying on iCloud Calendar has caused and continues to cause a lot of pain as these unwanted invites hit users' email inboxes and trigger a notification. As noted on Reddit, the iCloud Calendar web app seems to have gained a new link for reporting spammy calendar invites and blocking their senders.
This feature will be rolling out to the stock Calendar app on iOS devices soon, an Apple representative allegedly told a disgruntled customer.