Grouped emails generally come from mail delivery services and the sending server is set to send individual messages to recipients, such that the list of recipients is not needed. A reply goes back through the mail delivery server which then sends the response to the individuals. That is different from a mailing list, such as on Thunderbird, where all recipients receive the full list of recipients

Thanks, David. That explains why I can't uncover who is on the committee where I've become a participant.~ Janice