I somehow acquired a tracking mechanism on my Gmail which had 2 send buttons (blue icons) - one send & track, the other send & don't track at bottom left of the screen.. There was also an outline icon representing an envelope at top right of the screen. Clicking on the latter at any time gave a list of sent & tracked emails with white backgrounds for 'unopened' and green for 'opened. with details around this.
About a week ago, this facility disappeared as fast as it appeared and as I was used to it to track emails, I was upset! I have searched about 20 other trackers but none look like the one I lost. They track every email and I don't want that. I (hopefully) attach my memory of what the send screen looked like plus an extract of the list of opened/unopened accessed via the envelope icon. Can anyone identify it? I have a feeling it was an extension which was removed - name something like Inmail or Inbox Gmail or similar.