Hi,
Rather curious case, but I'll try to explain as detailed as possible.
User A and User B previously had full access to a shared mailbox. They are now replace by User C and User D. User A and B are fully removed from anything i can possibly think of regarding access.
So the case is, User C sets up a meeting as the shared mailbox, in the shared mailbox's calendar in Outlook. She then invites herself (User C) and User D.
When User C then accepts the meeting invite in her own mailbox, a confirmation mail is sent to User A and B stating that User C has accepted the meeting. Same happens if User D accepts the meeting.
User A and B has no access to this shared mailbox what so ever unless there is something im missing.
Things i have checked:
Mailbox delegation in Exchange Online AND our local exchange.
Checked for any rules client side and server side. For all users including on the shared mailbox
The shared mailbox local AD object, User A and B had some special permissions there, but problem still occurs after removig.
Calendar permissions on the shared mailbox.
Is there anything I'm missing here?
Hope the explenation is understanding.

