My message advancement (Personal website)

Make ‘SPC’ to advance to the next page or message, never crossing threads.

(with-eval-after-load 'notmuch
  (keymap-set notmuch-show-mode-map
              "SPC"
              #'notmuch-show-advance))

Make ‘S-SPC’ return back to the previous message.

(with-eval-after-load 'notmuch
  (keymap-set notmuch-show-mode-map
              "S-SPC"
              #'notmuch-show-previous-message))