I hate the new mail system

OK, it's official. I rarely criticize mail interfaces, because they're usually mostly innocuous. However, today's change makes life a lot more difficult. In the past, it was simple to direct a reply to an individual instead of to the list because the originator's address was right there in the From: header. As of today, the list address is substituted for that, so that it is impossible to respond privately unless you happen to have a bunch of old messages archived and the person to whom you want to respond is someone who has written previously. Is this a conscious choice, or a configurable with a different default setting in a new mail system than was previously in place? However it came to be, it greatly diminishes communications quality (IMAO).