turn off external calendar invitations

Welcome to the Apple Support Communities!

I understand you are receiving spam calendar invitations. Here are a couple of ways to address them:
iCloud: Report junk Calendar invitations
Change Calendar Preferences to send invitations as emails:

1. From your computer, using Safari, go to www.icloud.com
2. Enter your Apple ID and password to log in
3. Click the Calendar app
4. In the lower-left corner, click the Action icon (looks like a gear)
5. Click Preferences
6. Click Advanced
7. In the Invitations section - "Receive event invitations as" choose "Email to (your email address)"
8. Click Save

Happy Holidays!