I had some ghost mailboxes in my Outlook 2013 mailbox list. I had full access to these mailboxes, but removed it some time ago, but they are still there. If I click on them and try to remove them, they cannot be removed. I found the link below which had the following instructions which solved the problem. The hardest thing to solve was going through all of the “solutions” that didn’t actually understand the problem.
- Open ADSIEdit (WinKey R to open Run and type adsiedit.msc)
- Connect to the Default Naming Context. (Click OK)
- Locate the mailbox that you once were granted Full Access Permissions and …
- Right-click on the object, view properties.
- Scroll down to MsExchDelegateListLinked attribute.
- Click Edit, select the User Object and click Remove your information.
This link below is where I got the solution