If you feel like you just can't wait, then send it. But, if you will feel worse if T doesn't email you back, then I would wait. If you just want her to read it and that will help you, send it.

I usually send my emails, even now that my T is away, because I feel better knowing that I got it "out of me" and into my therapy, if that makes any sense. You have a lot to talk about in your session, so maybe it will help to let your T know ahead of time via your emails.