In this article you will learn how to add a shared or secondary mailbox in the Outlook desktop app for macOS. This guide also shows how to turn off “New Outlook” mode, which is recommended for the best view of the shared mailboxes.
Shared mailbox access is granted through a Shared Mailbox Access Request
Before You Begin: Turn Off “New Outlook” on Mac
It is recommended for the best view of the shared mailboxes to switch back to Legacy Outlook before adding shared mailboxes or changing permissions.
Outlook 16.58 or newer
- Open Outlook for Mac.
- On the menu bar, select Help > Revert to Legacy Outlook.

Outlook 16.57 or older
- Open Outlook for Mac.
- Turn the New Outlook toggle in the top right OFF.

Add a Shared Mailbox in Outlook for Mac (Recommended)
Share Specific Folders: Step 1 for Mailbox Owner
Share Specific Folders: Step 2 for Recipient
Quick Troubleshooting
- Mailbox not showing: Quit Outlook and reopen. Large mailboxes can take several minutes to load.
- Error “The set of folders could not be opened”: Confirm shared mailbox approval and correct permissions. Then try signing in again.
- Using New Outlook: Switch back to Legacy Outlook. See the first panel.
- Folder access missing: Owner must set Folder Visible for Inbox and Folder Visible plus Create Items for Deleted Items.
Additional Support
For further assistance with Outlook for Mac and shared mailboxes, visit Microsoft Support Page
If you experience sign-in or TRU account-related issues, contact TRU IT Service Desk:
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📞 1-250-852-6800
📞 1-888-852-8533 (Toll-Free Canada/US)