I'm guessing you didn't mean it this way, but this comes across as a bit judgmental. A decent number of people are in therapy to get in touch with their own needs, and I don't know that it's helpful to call someone needy or clingy for wanting contact with a kind, stable person. I agree that the OP should talk to their T about what's going on with email, but the conversation should probably be centered on how both people can function comfortably in the therapeutic relationship. It doesn't help to just tell somebody to not be needy.