After 12th Planet Press's success with their publication 'Letters to Tiptree', they're now open to letters to (Octavia) Butler:
[I]n recognition of Butler’s enormous influence on speculative fiction, and African-American literature more generally, Twelfth Planet Press is publishing a selection of letters and essays written by science fiction and fantasy’s writers, editors, critics and fans.
They're paying 5 US cents per word from letters between 1,000 and 1,500 words. Deadline is 8th of January, 2017.
Literarium link is here: https://literarium.net/market/twelfth-planet-press/letters-to-octavia-butler