A shared mailbox is a mailbox with a unique email address that multiple employees can access. Emails sent to the email address will arrive in its Inbox, and emails can also be sent from the shared mailbox address. Like an employee's mailbox, a shared mailbox has folders for Drafts, Sent Items, Deleted Items, etc.
If you have been granted access to a shared mailbox, please wait one hour, then close and restart your Outlook client. If the mailbox still does not appear in your Folder pane in Outlook after restarting, it can be added manually via the methods in this section.
Articles (4)
How to access and send from a shared mailbox in Outlook 2016 or 2019.
How to access and send from a shared mailbox in a web browser.
How to access and send from a shared mailbox on a Mac.