FYI, you can have tree-threaded conversations in email too. Thunderbird has pretty good support for it, which is why I use it for mailing lists.
The only reason more people don't know about this is that support for it has always been poor at best in Outlook, which is what most of the world uses as their email client.
In Thunderbird the option is View > Sort By > Threaded, which you need to set per folder (it's off by default). I set up filters so I have one folder per mailing list.
This is not the same as Outlook's group-by-conversation feature, which is based on subject lines. It is full tree-threading based on the in-reply-to header, same as Usenet.
The only reason more people don't know about this is that support for it has always been poor at best in Outlook, which is what most of the world uses as their email client.
In Thunderbird the option is View > Sort By > Threaded, which you need to set per folder (it's off by default). I set up filters so I have one folder per mailing list.
This is not the same as Outlook's group-by-conversation feature, which is based on subject lines. It is full tree-threading based on the in-reply-to header, same as Usenet.