Add shared mailbox in Outlook
When a user is added to a shared mailbox this usually appear with no actions needed in about 60 minutes or so. If not then the user need to add this by themselves by following the instructions below:
From Outlook go to Account Settings then "Manage Profiles" :
Proceed to "Email Accounts" :
Pick the account in need and press "Change account" :
Click on "More Settings" :
From there go to "Advanced", then "Add" and type the name of the shared mailbox you are missing:
If you can't access then either the spelling is incorrect or you are using the wrong account, if not contact support for further guidance.
Now you are done!