- /* For the parent of this message, use the last message ID of the
- * References header, if available. If not, fall back to the
- * first message ID in the In-Reply-To header. */
- if (last_ref_message_id) {
+ /* For the parent of this message, use
+ * 1) the In-Reply-To header, if it looks sane, otherwise
+ * 2) the last message ID of the References header, if available.
+ * 3) Otherwise, fall back to the first message ID in
+ * the In-Reply-To header.
+ */
+
+ if (strict_message_id) {
+ _notmuch_message_add_term (message, "replyto", strict_message_id);
+ } else if (last_ref_message_id) {