[sp4rki]

Ahh I understand. I generally don't use threading (I rather threat emails as a standalone items), but I can see why you'd find subject threading annoying. I tend to filter emails and reroute different types of emails that don't belong in my inbox to other systems, so I don't see a need to be as stringent on the requirements for threading. That being said, I don't know if any clients that would fulfill your expectations. I guess you're stuck with Thunderbird!