MacMail in classic mode does not show reply in Big Sur
I use to be able to click on the arrow in front of mail I replied to and see the reply. Now it just shows the current e-mail in a new window. Why?
Mac Pro, macOS 11.1
It still does, sort of, but not like the non-column layout (I think they renamed "classic mode" to "column layout" in Big Sur version of Mail). You have to click on the message and scroll down to see your replies below it (in the Preview pane). Alternatively, you can choose View > Organize By Conversation and deselect it. Then your replies show up in the list of messages. I know none of this probably helps you. Sorry.
In non-classic mode, to the right of each message is an expansion icon (a small v arrow in a circle). If you click this, you can see a list of messages in the thread, including your replies. Again, not as good as clicking a button to seeing your exact reply to the exact message from the other person: