Based on a message sent by a moderator of a group I manage: members must take the initiative to unbounce themselves. When they receive bounce probes, they will get a link to unbounce their address, and that must be communicated when sending a message to affected members directly. It could pose an issue if folks do not use the web interface, but that¡¯s not yet tested.
i am an owner of multiple groups...yesterday¡¯s gmail outage has caused many to bounce. i have sent bouncing probes but they are not solving the problem.