Shared Mailboxes are on option for a group of users to access on inbox for a department email address. They also allow for users to send email from the shared mailboxes' email address.
Accessing a Shared Mailbox
Once a user has been granted access to a shared mailbox, the user should wait one hour, then close and restart their Outlook client. If the mailbox still does not appear in your Folder pane in Outlook, it can be added manually via the following methods: