Govan1x, there is a layer of misunderstanding here that I am not qualified to correct.
However, having his email address on your PC, both in the past and in the future, does not put you, or your PC. at risk.
The person, or organisation, which hacked his PC will have all the information that he had on you at the time in the past. BUT, they will also have the same information on several million other PCs as well and they may never get round to looking at your bit.