Well, as we're being detectives:
The 40 email addresses seemed to be listed in 'AQC course order', most recent first. There were only five addresses listed for 29th May's AQC but based on Dankersoe's list we'd expect 6. Incidentally all 10 on my course were listed.
I really wouldn't devote so much thought and effort to this kind of thing if my current job wasn't so very dull.