Another confusing factor with the Auto-Message is that it appears to be coming from the Owner of the member's group rather than from GROUPS.IO itself as can be seen in the FAQ sample message. In our case that was a major factor in the member's reaction. I find it unusual and confusing for the "email group service" to send a message in the name of one of its groups.
(Whom it may concern)
“If you will not fight for the right when you can easily win without bloodshed, if you will not fight when your victory will be sure and not too costly, you may come to the moment when you will have to fight with all the odds against you and only a small chance of survival. There may even be a worse case: you may have to fight when there is no hope of victory, because it is better to perish than to live as slaves.” — Winston Churchill