What I think is a usability and a design regression is that now all three (CC + BCC + Reply-To) are all visible when any one of them has any data.
And this regression is having an impact because CC is used quite often, BCC less so, but "it's just like the CC although not exactly", but the Reply-To is "a whole different thing so why in the world is it visible".
I agree with that. {*}
I was even thinking about use cases when Reply-To: would be needed to be used "on demand". I had problems coming up with those, but decided that there must be some, so, it's probably better to have that flexibility.
My vote is still for the write-in From: [wink-wink!...].
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{*} I would just note that Bcc
should be used more frequently by people. I use it
very frequently, to avoid exposure of large lists of addresses and also to avoid unwarranted "Reply-All" by some thoughtless people.
Re: Just a quick clarification: I am not sure if in the earlier versions it was possible to open "Reply-To:" "on demand" (as it could be done for Cc/Bcc), i.e. when it is not set in the settings.
It was, had a separate menu item from the "show CC/BCC" menu item.
It doesn't matter to me (it's a purely "academic" question at this point), but I looked again and I don't think there was/is a way to bring up "Reply-To:" in 1.6.x "on demand", even via a menu. The only way I could find to show it is to configure it in the settings. Then it would be shown, and you can edit or delete it. But if it is empty in the settings, you cannot bring it up to "write in".
So, the possibility to "expand" "Reply-To:" on demand is probably useful to some users.