The HR website states:
Your email account
After your last day at the University, your email account will be disabled and you won’t have access to it.
If a retiring staff member is going to continue working for the University, the department or school would need to progress granting emeritus status or visiting status via HR. We would advise that this process is started well in advance of the member of staff retiring.
Alternatively, if approved and appropriate, we will allow the account to remain active with an 'out of office' for one month; this should be set up by the retiring staff member before they leave. There will be no access to the account during this time.