Brian Vogel <britechguy@...>
This will almost certainly help, but might I ask whether the subject matching is "perfectly exact" or fuzzy? There are many instances on some of the groups I frequent where someone will accidentally have knocked off, say the "R" on "Re:", or something similar but where the rest of the subject is still completely intact. I can't think of a single instance where this should not result in the message being threaded into an existing active subject (and where I know that the message does not have threading information before you'd even get this far into the algorithm).
This brings up a related, interesting, and almost certain to be controversial topic: I have seen e-mail clients that thread when threading information is available in the message header regardless of whether or not someone has changed the subject when the message originates via use of "reply" which causes the threading information to be included. The only way one escapes a conversation/thread to form a new thread via e-mail is by creating a new message, using a new subject, and employing "cut and paste" if desired to transfer any context from a thread that one may be launching a spin-off from. Has that ever been considered here, or could it be?
Most of the thread splitting I'm observing and fixing is the direct result of user ignorance of threading conventions and netiquette. They treat the subject as an extension of the message body, and will prepend or append something to it that's meant as an embellishment, but with no idea that this would trigger an entirely new thread. I believe that some of this also arises because some e-mail clients thread strictly on header information when that's available and ignore the subject altogether, so they're accustomed to seeing mixed subjects under one conversation thread.
There could be an argument made that this would be the best way for Groups.io to thread based on my limited experiences on the groups I frequent. Others, of course, may differ, but they also may strongly agree. I'm really curious about what other people are experiencing with regard to users changing subjects willy-nilly with "cute bits" when the actual message they're sending is clearly just the next in the line for an existing conversation/topic/thread.