I'm using color coding along with a virtual folder to indicate messages that I have replied to but are waiting for a reply back.
e.g You email me, I reply and color your message blue. I have a virtual folder called [@Waiting for reply] which is filtered to only show blue emails.
Is there anyway when I color your original message blue to tell TheBat that any messages which are in the same thread (either now or subsiquently) as the blue message should also be either colored blue or allowed to be shown in the virtual folder ?