Open Outlook and go to File > Account Settings > Account Settings...
The below box will appear:
To add a mailbox:
Click on Change... > More Settings > Advanced > Add... > mailboxname@rodo.co.uk
Once added, click Apply > OK.
Outlook should refresh in the background and you can then close the other dialogue boxes.
If the mailbox hasn't appeared, restart Outlook.
Please note that you can only add a mailbox which you have been given access to.
If you have any questions or issues, please contact the helpdesk.