Step 1: Open Preferences

Select Outlook in the top menu bar and then select Preferences...

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Step 2: Open Accounts

Select the option for Accounts under the Personal Settings section.
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Step 3: Open Advanced Settings

In the bottom right corner of the page select Advanced...

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Step 4: Add an Additional Mailbox

Select the Delegates tab.

Under the Open these additional mailboxes section select the + icon.
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Step 5: Add the Mailbox

In the Choose a Person window enter the email address for the additional mailbox.

Select the desired mailbox from the list and then select the Add option.
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Once added, the mailbox will show up under additional mailboxes.
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Select OK.

Step 6: Allow Auto-Discover

If prompted to allow Auto-Discovery please select the check box for Always use my response for this server and then select Allow.
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Step 7: Access the Mailbox

The new mailbox will automatically appear in the left hand menu within Outlook.
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