Hi,
I've had therapists who did not email and were not interested in communicating that way (I think because they didn't want the potential for abuse of their time.) and my current therapist who PREFERS to communicate by email.. she told me this at our first appointment. (I feel very lucky to have found her!) I would say that it wouldn't hurt to ask for an email and if you get one you may want to clarify the boundaries. Can you email about appointments, what if you have an issue you are dealing with and want her feedback, etc. You may try explaining to your T that the best form of communication for you is by email since your calls go to voicemail and you don't want to have your T playing telephone tag.