Excuse the Newbie question but I am a newbie: Are the threads held together based on the text of the subject line or is there some magic in the header that makes it work? The reason I ask is that I get the MIME digest and if all that is required to maintain a thread is the subject line--no problem but If there is some kind of non-subject line tracking involved, how do I reply from a digest.? I'm using TB .4 and it forces a reply to the entire digest and won't allow a reply to a single message. John