I'm experimenting with Microsoft Graph to create calendar events in Microsoft 365. I have noticed that when I specify attendees, only attendees who have non-M365 domains actually receive invitations. Attendees who have a "onmicrosoft.com" domain, or some custom domain tied to M365, receive nothing. What's the reason for that?
Also, I would like to know if there is a way to just not send any invitations at all. In Exchange Web Services, sending invitations is optional when creating a meeting.