Have you been seeing unsolicited offers in your Apple Calendar? iOS or MacOS users have recently found their Calendar infested by fraudulent invitations -- the problem exploded over Black Friday weekend. Spammers exploited a loophole in Apple's iCloud's default settings, which allowed senders to bypass email and push calendar alerts directly to Apple iOS and MacOS users' Calendar app.
The trouble is that unlike spam email, you can't just delete or block these invites; your only options are Accept, Decline, or Maybe. Do not choose any of those options: They notify the spammer that your account is active, which can then open the door for more spam. But never fear, there are two workarounds that can delete the spam you already have and let you block future invitations.
Delete spam Calendar invitations
First, do not hit Decline. Get rid of spam by moving the invitations to a new calendar that you can delete without sending any notification to the spammer.
1. Launch your Calendar app, then tap Calendars on the bottom rail.
2. Scroll down to the iCloud calendars list, tap Edit, and then tap Add Calendar.
3. Name your Calendar. (I named mine Scams.) Then keep tapping Done till you return to the Calendar screen.
4. Move the event to the new Calendar by tapping the event, expanding the Category bar, and selecting the calendar you just created.
5. Open your new calendar, scroll to the bottom of the Edit Calendar screen, and tap Delete Calendar.
The spam invitation will be erased without alerting the sender that your account is live. Repeat this process for each of the invitations you've received.
Block future spam invitations
By default, Apple shows new Calendar invitations in app, where you can't delete, only decline. Change this setting so that invitations go to your email instead.
1. Log in to your iCloud account via your Web browser. (You can't change the following setting in app -- you have to go to icloud.com.)
2. Launch the Calendar app.
3. Tap the Settings icon in the lower-left corner and select Preferences.
4. Under Preferences, click the Advanced tab.
5. Go to Invitations, then change "Receive event invitations as:" from "In-app notifications" to "Email to [your iCloud account address]" and click Save.
Now all calendar invitations will go to your email account, where you can easily erase, block, or report them.