Access a shared mailbox.
If you have full access to shared mailbox, this is how you add it to your folders for access. Open your Outlook on the web by going to [https://outlook.office.com]. Once logged in right click Folders on the left hand side menu.
Choose Add shared folder.
Start typing in the email address of the mailbox you have full access to. Once completed click the Add button.
Your new mailbox should now be showing.
If you are using the Outlook application on your pc, please close and reopen and the folder should appear once the above has been completed.