Hello,
I'm having an issue where some emails are being assigned to System user without ever being put into the queue it's supposed to be according to the queue's Incoming Email field in the admin center.
I found Service Desk referred to in Mailbox field doesn't exist, as shown below. The image on the right shows what happens when you click Service Desk, and tell it to show the details of the error. This Mailbox field is unable to be edited by admins and the owner of the queue who is also an admin when interacting with this field, and it's unclear if it can be adjusted from any other location within D365 CRM. Any guidance is greatly appreciated.