Open Shared mailbox in Web Outlook.
1. From Outlook Web, you can click on Open another mailbox, then enter the email address for your shared mailbox address.
The dialog box should appear, enter in the mailbox that you have access to review
2. Manually add shared mailbox to Outlook:
3. You will now see a new Tab under Mailbox with the Shared Mailbox you just added. Click the > to access the Mailbox.
Choose the File tab in the ribbon.
Choose Account Settings, then select Account Settings from the menu as seen below.
Select the Email tab.
Make sure the correct account is highlighted, then choose Change.
Choose More Settings > Advanced > Add.
Type the shared email address that you have access to review.
Choose OK > OK.
Choose Next > Finish > Close.