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Open Outlook.
Right-click on the account name or shared with me folder in the left navigation pane, and then choose Add shared folder or mailbox.
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In the Add shared folder or mailbox. dialog box, type the name or email address of the shared mailbox, and then click Add.
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You can view the shared mailbox under “shared with me“ option.
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Notes:
The mailbox folders and contents can take an hour or two to appear if your permission to access the shared mailbox was added on the same day when you add the shared mailbox to Outlook.
Sent messages from this shared mailbox will be saved in the Shared Mailboxes' Sent folder
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