Role Mailbox issues:
a/ If you are new to role first check you have access to the role mailbox and that you are using the correct address as its setup address. Relevant people who can check this for you on the toolkit are:
maths helpdesk, Head of Department PAs, Manager of the HR office, DAMTP BOM's PA.
b/ If you still cannot get the mailbox to add to outlook then contact the UIS service desk. The UIS run the role mailbox system. It's helpful to include in the email a screenshot of the error message you received.