At a previous job I had someone raise a ticket that other users were not getting out of office messages from the users previous (temporary placement) employer. Needless to say we couldn't legitimately raise a ticket with other organisation. User (VIP) would not let us close the ticket as would not accept our explanation and they could not do this as no longer working for them. Issue fixed by a careful bit of cross organisation cooperation (I knew who ran the other organisations Servicedesk). Intentionally a bit vague as this was UK gov help desks!