Can I get back emails from recipients who does not open my mails within a certain time?

I am moderator of a group. It is a closed group. Most members do not reply to mails making the group communication ineffective. Only a few interacts on regular basis. We want to remove those members who does not even read the mails sent from the group. So we want to get back the emails from members who does not open the mail for a certain duration so that we can knock them in other ways. How can we do that?