The way I understand it now, they attach an invite to an email that you don't even read, but it shows up on your calendar. Is it too much effort to open the attachment yourself? Normally you think twice about opening an attachment from someone you don't know.

Or the much more sensible, and MSFT way of handling it (in outlook)

ExternalUser: Hello here is a calendar invite I would like you to attend, please confirm or deny

User: Thank you, now I can verify the request and choose to add this to my calendar or not

> Because you work with people outside of your company, support, vendors, sales people etc.

If I work with them, I would have them whitelisted. If I've never even heard of them they have no business sending my devices calendar invites.

Boss: Why aren't you working on that project I gave you?

You: Some stranger in Indonesia invited me to a sales meeting instead.

Boss: If I need you to go to a sales meeting with someone from Indonesia I'll tell you to! Clear your desk!