On Mon, Jan 6, 2020 at 12:56 PM, BarryS wrote:
A member of my group recently sent an email message to someone not in our group, and cc-ed the message to our group, using our full groups.io address (something he has repeatedly been told not to do, but he persists!).
In my groups(s), behavior along these lines will get someone placed on permanent moderation, and possibly banned.
The recipient replied using "Reply All", resulting in his reply being received by everyone in our group, even though the sender isn't in our group, and is not therefore authorised to post to our group. Not only that: all subsequent "Reply All" exchanges between group and non-group recipients were sent to everyone in our group. I didn't realize this was possible.
You can keep non-members from posting to your group. See Admin>Settings>Message Policies, first checkbox. Uncheck the box and non-member messages will be rejected.
This setting will not keep people who are already members from CC-ing the group when sending a message/reply to a non-member. But again, if you place such people on moderation then you can head off the side conversations before everything goes haywire.
Bruce
Bruce