When to Use?
If someone has been allowed to access a mailbox but can't see it in their Outlook application, they can follow the steps below to resolve the issue.
Procedures
Outlook for Windows
- Close Outlook on computer
- Right click the start menu in lower left hand of screen and click "Run"

- Type Outlook.exe /safe and click Ok (note the space between Outlook.exe and /safe).

When Outlook opens in safe mode, you can find the mailbox listed under the main Inbox.
- Reopen Outlook as you normally would by clicking on the Outlook icon.
Once Outlook opens, you will be able to see the mailbox listed.
Outlook for macOS
- In Outlook go to File > Open > Shared Mailbox
- Enter the email address of the account you want to add to your Outlook desktop app
- Select the account and click Save

Alternatively:
- In Outlook's Tools menu, choose Accounts, and select the account that has access to the mailbox.
- Select Delegation and Sharing
- Choose Shared With Me tab
- Choose + to add a shared or delegated mailbox