David,
Administrators can set the lists up so that replies go to the author, or to the list, or both, or "user decides" - moments ago I just set my googlegroups list to "user decides" because if I don't set it that way the author's email address is hidden - even from me - the list owner!
Email lists are strange. Gmail doesn't send you back your own posts, which was the original setting "way" back in 1980s when everyone was on a 300 baud modem and phone lines. Conserve valuable bandwidth in those days. Now sending you your own message takes a few milliseconds.
I still use mutt and thunderbird, both have "bounce" functions because sometimes my list subscribers think they have to send their emails to me for forwarding to the list. Bouncing an email makes it look like it was sent by the original sender to the final addressee - which in my case is always the email list, but it can be abused to fool people, Person A sends me and email, I bounce it to Person B and Person B thinks it was sent directly from Person A. You can see it came through me if you look at the headers.
I did have my email list set up that way in 1994 when I started that list as a "one way" email list. Finally when google announced it was doing free lists, I jumped at the chance. I also printed newsletters using a Commodore 64 and GeoPublish - wow that's going back some.
73
DR
N1EA