I email for a lot of different reasons. When email privileges were discussed early in therapy, it was conditioned upon my agreeing to not expect a response.

Initially I emailed a lot because even without a response, it left me feeling like I had talked to her. During the phase of therapy where I was one big open wound, I wrote her a lot about my pain between sessions. I also often email her after therapy whenever a lightbulb goes off or I get an insight after I've left.

Whenever she responds, it's usually very brief. I think therapists, because of their training, are more acutely aware than most of us that there is an inherent danger in written communication because you can't hear tone of voice or see facial expressions. My guess is that this is why your therapist is so especially polite. He's protecting the relationship for your benefit by ensuring he doesn't inadvertently come off in a way that you interpret as hurtful.