How to set up a shared mailbox in new Outlook
After your organization admin has added you as a member, close and restart the new Outlook. The shared mailbox should automatically appear in your folder pane on the left. In the new Outlook, shared mailboxes are added as subfolders under Shared with me within an account to which a certain mailbox is linked.
If the shared mailbox does not show up automatically in the new Outlook app, follow these steps to add it manually:
- From the navigation pane, select Mail.
- In the folder pane, right-click your account name or click three-dots next to it, and then select Add shared folder or mailbox from the context menu.
- Search for the mailbox. Type the name or email address of the mailbox you are a member of. As you type, Outlook will display a list of matches. Select the desired mailbox from the list.
- Once the shared mailbox is selected, click the Add button to complete the process.
The shared mailbox should now appear in your folder pane under Shared with me, letting you access its contents and manage emails. Click on the mailbox name to expand or collapse it, just like you do with your primary mailbox.
source article: https://www.ablebits.com/office-addins-blog/add-shared-mailbox-outlook/#web