On Mon, Aug 17, 2009 at 12:08:58PM -0700, Mun Johl wrote: > > I'm trying to find out what else I need to modify in the header so that > mutt can function properly. I think you also want to look at least at References: or In-Reply-To: (and sometimes Message-Id:). These are the only headers related to threading (and subject, depending on $strict_threads). Rocco