If you want to monitor the email from your primary mailbox and the shared mailbox at the same time, use this method. After you complete this task, the shared mailbox and its folders are displayed in the left navigation pane each time you open Outlook on the web.
Sign in to your account in Outlook on the web.
Right-click Folders in the left navigation pane, and then choose Add shared folder.
In the Add shared folder dialog box, type the name or email address of someone who has shared a mailbox with you, and then click Add. Or, type the name of the shared mailbox you are a member of, such as info@contoso.com.
The shared mailbox displays in your Folder list in Outlook on the web. 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 click Remove shared folder.