Ann,
A new member who had been on "no mail" just switched to individual
emails. When she tries to reply to one of the messages, it
automatically goes only to the person who sent the message instead of
to the whole group.
Some people using mobile email apps have reported that problem. It seems some apps ignore the "Reply-To" field that Groups.io puts in outbound message headers.
If that's her situation I don't know if there's a solution, unless there's an option in the app that could be changed, or an update to the app, or a different app she could use.
I use the gmail app on my Android phone, and it does not have that problem. If I remember correctly the members reporting the problem were primarily using the Apple mail app on iPhone.
Shal
Shal Farley