Is there a way to subscribe to all NEW calendar entries create by all users in my organization? Basically, whenever anyone in my organization creates a meeting invite, my app needs to be notified.
Our app needs this to work for both Exchange Online and On-premise.
Is there a way to subscribe to all NEW calendar entries create by all users in my organization?
No Subscriptions and always in the context of a Mailbox or Mailbox Folder (you need to consider your mailboxes will be spread across different servers in different data-centers)
As a workaround you could create a Transport Rule that catches any Meeting invitations and redirect them to a particular mailbox. Then just subscribe to events on that mailbox.