In older versions, when a note was added we received all the prior notes in the same email and that email appeared as a response to the email notification for the original report. Nowadays, we only get a short message with the content of the added note (which is much better! thank you for this) but unfortunately we lost the threading. That notification does not have the required In-Reply-To header and as such it starts a new thread/conversation in most mail clients.

Please add the required In-Reply-To header so that all mails for a given ticket appear in the same thread/conversation.