Hi there,
This request came up because our email service (Zimbra) and other mail clients (Apple Mail) are not always threading notifications from Tuleap.
The specific headers we're looking for are: "References" and "In-Reply-To".
One of our users provided this example to show the contrast:
Bugzilla supplies the References: and In-Reply-To: headers:
In-Reply-To: <bug-12345-10@http.abcde.com/bugzilla/> References: <bug-12345-10@http.abcde.com/bugzilla/>
Tuleap does not. That's why Tuleap messages don't thread.