1. From the top menu, select Tools. Select Accounts…
2. The Accounts window will be displayed. Select the Advanced… button.
3. Click on the Delegates tab. Beneath the people I am a delegate for section, select on the plus (+) button.
4. Enter the shared mailbox name or email address within the provided search field and select the correct result. Select Add.
5. You may be provided with an auto-discover prompt requesting that you allow the remote server to configure settings within Outlook. Select Allow.