Using the legacy format that message-make-in-reply-to generates by
default may be problematic, as is the case for lists.sr.ht.
#+begin_src emacs-lisp
(use-feature message
:config
+ ;; redefine for a simplified In-Reply-To header
+ ;; (see https://todo.sr.ht/~sircmpwn/lists.sr.ht/67)
+ (defun message-make-in-reply-to ()
+ "Return the In-Reply-To header for this message."
+ (when message-reply-headers
+ (let ((from (mail-header-from message-reply-headers))
+ (msg-id (mail-header-id message-reply-headers)))
+ (when from
+ msg-id))))
+
(defconst a/message-cite-style-format "On %Y-%m-%d %l:%M %p, %N wrote:")
(defconst message-cite-style-bandali
'((message-cite-function 'message-cite-original)