Is it possible he is really bad with emailing? My therapist is a terrible emailer. I use it for my own purposes, and almost never ask for a reply, but I know he's probably got a heap of unanswered emails he feels really guilty about. I don't mind this, as I'm the same. But I could totally see the potential for it to seem really hurtful.

Is it possible to ring him? That might be easier for both of you.