Ladies - thank you very much for your replies

It will take some time to publish the book - there is still much to do but I'll update the thread as soon as there are any news!
Why were the letters not published earlier? Well, as you can see in my post: Toni lived very long

She had always refused to talk publically about her close relationship to the Tsarina - though many people knew about it and inquired. Her grand-daughter, now in her sixties herself, is a keen family-researcher and has done much to the huge and important collection of letters and documents which contains - as written before - much more than the letters from Alexandra.
After the publication of "Alix an Gretchen" she thought she could do the same - especially as the early letters to Toni are indeed outstanding. I've never seen Alexandra writing in such an open voice (only exception: to her husband). Much later Ernst Ludwig of Hesse told Toni that she was the only one "really knowing my sister".
The earliest document surviving dates from 1887 the last one is a telegram fr 1913.
In later years Alexandra - of course - had to be careful of what she wrote due to the insecure way of postage.
There will also be quotes from letters by Princess Irene to Toni - and many photos from the 1880ies and 90ies including some of Alexandra's Hessian family.