Thanks everyone.
There are always going to be differing opinions to something a T writes. I don't mind anybody's response and at no point on this thread have I felt criticised or like my T is being criticised.
I think what is important for me is that this email relates to me, my T, our relationship and our history. He wrote it to me and I found it helpful, thoughtful and honest. That is what matters to me, and I suspect to him too.
Ruh Roh, thanks for what you wrote; you have a better understanding than most of my relationship with my T through the years (and an enviable memory!). You are right that there is so much history behind this point in our relationship, and that adds extra layers of depth to the letter which might not be apparent on the surface.
I really appreciate everyone taking the time to share their thoughts on his response, I've found it really interesting and useful to hear other perspectives.
I replied telling him that the email helped to ease my anxieties, as I felt he understood me. And thanking him for it.