Things like this, along with tools like t-prot¹, allow you to live the mail you want while still interacting with others ;)
what i find fault with in the lwn article is the "attack" on gmail. gmail has its reasons for doing the things it does, good reasons.
i actually liked mulberry quite a lot. especially the feature where 'reply' brings up an interstitial allowing you to select to/cc/bcc for each recipient. another aspect of email completely lost on normies. but it's day has passed.
I take your point, very well. But a fundamental disagreement we have is your generous opinion of the 90 %ile user's ability and desire to become an email expert. The loss of that battle was recognized in September 1993.
gmail didn't relinquish its duty to educate users as it became popular; it became popular (in part) because it did things in a simpler way, that users didn't have to "learn" how to use. The vast majority of folks do not care about such trivialities as following a thread. It requires forethought that they do not want to invest.
You have to meet users where they are at. One can wish for better users, sure. That's not a winning strategy.
As well, I still maintain it's unfair to pick on gmail. They had to follow Outlook. Outlook willfully broke threads for other MUAs by not including In-Reply-To headers. That was just evil. At least gmail generates In-Reply-To and References headers! Which Outlook drops. Outlook should be the bogeyman for your article, not gmail!
Thank you for informing me about the role of Outlook in this. I used Gmail as my example because it seems to be taking over, at least for “normies”, as you call them. So the average person’s idea of what email is comes from experience with Gmail. It’s possible I’m underestimating the importance or prevalence of Outlook, as I deal less with corporate types than academic and publishing types.