Setting up a Shared Mailbox in New Outlook (Mac) - Exchange Online
“New Outlook” is a new version of Outlook for Mac with a redesigned interface.
To open a shared mailbox you have been granted permissions to access, first open Outlook
Select File > Open > Shared Mailbox
Search for the name of your mailbox and a list of similar names will appear, highlight your shared mailbox and click Add
The shared mailbox will then be added below your primary mailbox
Alternative method:
In the Tools menu select Accounts and select your own email account
Select Delegation and Sharing
Choose Shared With Me tab
Choose + to add the mailbox
Search for your mailbox and select Add
If upon following these steps you encounter an error saying: “Cannot open this mailbox - this mailbox has already been added”, press Cmd+Q to quit Outlook, then re-open it.
If you are still not able to open the mailbox it is likely you don’t have permissions; please ask someone with existing permissions to apply on your behalf to the CSCS Service Desk.