I have a co-worker that refuses to use any chat service at work. You have to email him if you need him and he will get back to you very quickly if he's not busy

I have a co-worker that refuses to use any chat service at work. You have to email him if you need him and he will get back to you very quickly if he's not busy. That forces us to make a real case before emailing him because emails are more like a serious business!