"Read" feature on group emails

The ability to see whether each recipient in a group email has read the message - without relying on read receipts, would be useful. This helps us identify who hasn't seen important emails and follow up accordingly. It's a crucial feature in our current workflow but is missing from most modern email clients.

Recipients would have to be on the same platform (I suppose gmail or outlook doesn't natively have that feature), and that seems to be an acceptable compromise.