If you already have permissions to access another mailbox, follow the steps below. You can monitor the email from your primary mailbox and the shared / delegated mailbox at the same time. The shared / delegated mailbox and its folders are displayed in the left navigation pane each time you open Outlook Online.
NOTE: The shared / delegated mailbox will display under your primary mailbox.
Step 1. From your Office 365 landing page, select and open Outlook
Step 2. Right-click your primary mailbox, Folders, in the left navigation pane.
Step 3. Choose Add shared folder
Step 4.
- In the Add shared folder dialog box, type the name or email address of someone who has shared a mailbox with you
- then select Add
The shared mailbox displays in your Folder list. You can expand or collapse the shared mailbox folders as you can with your primary mailbox. You also can remove the shared mailbox from your Folder list. To remove it, right-click the shared mailbox, and then select Remove shared folder.