I am having the same issue. I get a "Gmail return" for all posts to our io.groups forum, including my own posts.??
I haven't changed any settings, either to my own account or as a moderator. I checked to see that this was the case.
I hope Mark will re-attack this issue as it's a problem for anyone with high volumes of email. Thanks.
Michael Jaross
mtbakerbees@io. .....