On 20 Jan 2007, at 14:06, jelmore at elmoredesign.com wrote: > Looking at a message source, I don't see any header that would > indicate > that a subject belongs to a thread with a different subject. So how is > that done? From the message you replied to: In-Reply-To: <20070119222529.1611387305 at smtp.mac.com> References: <cf4239a3a677dfe8f96b394b441e507d at comcast.net> <515A4AB4-10D2-4E5A-9111-26B194CED62A at earthlink.net> <6E0F93B2-421E-41FC-936A-8BBD7C224063 at mac.com> <13fd79f6e16d5556fd2c34ffb9731619 at comcast.net> <C668A83E-56DC-47F1- BEFF-E2FF57EBDC62 at speakeasy.net> <20070119222529.1611387305 at smtp.mac.com> From these one can ascertain all replies previously made in a thread. I see that your web-based email program deletes these headers. I'm not sure if that's correct behaviour. Stroller.