(with-eval-after-load 'notmuch
  (setopt notmuch-search-result-format
          (list (cons "count" "%9s ")
                (cons (lambda (_ thread)
                        (concat
                         (propertize
                          (if (member "unread" (plist-get thread :tags))
                              "*" " ")
                          'face
                          'notmuch-tag-face)
                         " "))
                      "")
                (cons "subject" "%s"))))