On Wed, 6 Jul 2011, William Scott wrote: > If a new subject does not carry over the "In-Reply-To:" header from > the original post then all should be fine. Your message also had a "References:" header In-Reply-To: <[log in to unmask]> References: <[log in to unmask]> <[log in to unmask]> which appears to provide information that threaders might use. I'd recommend removing those headers too. http://www.jwz.org/doc/threading.html describes one threading algorithm -- Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge [log in to unmask] http://www.dpmms.cam.ac.uk/~werdna