In earlier Versions of Apple Mail if there are multiple mails of the same content, i.e. in Inbox and in Sent, Mail would show "1 duplicate" in the upper right. This seems to be gone in El Capitan Mail 9. Now there are multiple Mails with exact same content (Cmd-Shift-D) but sent to different addresses next to each other in the Sent folder. How can I set Mail back to show them as duplicates?
Here's the link to the discussion about it. https://discussions.apple.com/message/29070991#29070991
It has been modified to group only messages in that actual conversation and the feature we all loved is now gone.