How to manually add an additional mailbox on Webmail
Under normal circumstances, any additional mailboxes that you have permissions to view would already be visible in your Outlook. If this is not the case, these are the steps you would follow to be able to add a new mailbox to your Outlook.
Click on the Add Shared Folder option from the drop-down menu.
Enter the email address of the mailbox that you want to add. Select it from the drop-down list.
Click “Add”. You will now see the new mailbox on the left hand side column.
If you try to open it to view it and receive the following error, “Can’t complete your request”, this is because your account does not have permissions to access this mailbox. Please contact your manager for them to request to have you added to it.