Merge branch 'MDL-67772-email-thread-headers-MOODLE_402_STABLE' of ht…

…tps://github.com/brendanheywood/moodle into MOODLE_402_STABLE
moodle · Feb 5, 2024 · 8af2a58 · 8af2a58
2 parents cea960e + 60c7936
commit 8af2a58
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/mod/forum/classes/task/send_user_notifications.php b/mod/forum/classes/task/send_user_notifications.php
@@ -485,6 +485,11 @@ protected function get_message_headers($course, $forum, $discussion, $post, $a,
             } else {
                 $headers[] = "References: $parentid";
             }
+        } else {
+            // If the message IDs that Moodle creates are overwritten then referencing these
+            // IDs here will enable then to still thread correctly with the first email.
+            $headers[] = "In-Reply-To: $rootid";
+            $headers[] = "References: $rootid";
         }
 
         // MS Outlook / Office uses poorly documented and non standard headers, including