My T always responds to my emails with an email. I have written him some fairly long messages. His responses are always short. Generally in the next session he says something like "Can we talk about your emails?" I assume this is so we can cover the material in person so he can hear me talk about it. He does give me the option of discussing it or not. Once I was so mortified that I only talked about how sorry I was that I sent the email & how stupid I felt.

You can close at the end by saying "I would really appreciate it if you would write back if possible." That might prevent a call & should hopefully get you a response.