This is not so much about her letters, though whatever speculations we reach might shine some light on them. My question is, since she was black and her explanation to Mat cannot be trusted, what has she been up to? Do we know how long between her leaving Rand and meeting Mat? How did she find him, and why pictures of both Mat and Perrin? Can she track ta'verin and didn't know which she had found? What has she been up to? Maybe she entered the tower and moved the horn, and that's whats in the letter?