Private items aren't displayed in a shared mailbox in Outlook
In Microsoft Outlook, items such as email messages or meeting requests that are in a shared mailbox and marked as "Private" aren't displayed in the Inbox. This behavior is by design.
Only the sender can set the sensitivity level of the item. This option is unavailable in the recipient's Inbox.
To work around this issue, use any of the following methods:
Use Outlook on the Web (OWA).
Add the user as a delegate to the shared mailbox who has access to private items.
Add-MailboxFolderPermission -Identity firstname.lastname@example.org:\Calendar -User email@example.com -AccessRights Editor -SharingPermissionFlags Delegate,CanViewPrivateItems
Although this cmdlet specifies Calendar as the target folder, it also enables you to view private items in the Inbox folder.
- Select File > Account Settings > Delegate Access
- Double-click the username of the delegate or select Add to add a new delegate.
- In the Delegate Permissions dialog box, select the Delegate can see my private items check box.
- Select OK.
In Outlook, add the shared mailbox as an additional account by using the email address and password of the user who has permission for that mailbox.
Make sure that automapping is removed and the mailbox is not added as an additional mailbox. To learn how to remove automapping for a shared mailbox, see How to remove automapping for a shared mailbox in Outlook for Microsoft 365.