Email Threading not working when a status changes and other conditions

Email threading is simply not working in many cases when an issue is transitioned or in various other notification conditions.

It seems that the "In-Reply-To" header for update emails are not matching those of the original email. As such, they show up in Outlook/Gmail as separate emails which quickly flood your inbox.

I believe the ideal action would be to have the header value match that of all notifications related to the same ticket-number.