Hi, I'm Robert and I'll be helping you with your computer question.
what is happening is that he has faked his email address and you can't block it because the one that is listed as coming from is not the real one
about the only thing that you can do is make a filter or rule that looks for something in the email such as his name and automatically deletes it as soon as it comes in
I can log in and do that for you but there is an additional charge.
or i can get you a page that gives instructions for creating rules or filters.