Okay, so I finally get a copy of a copy of the original email.
It's just a bunch of .jpg's of optical illusions. There's NOTHING executable.
So, I don't know WHERE the stupid .exe that is lurking in /temp came from, but it didn't come from that email.
I don't know WHERE they got the idea that there was a virus in that email (unless it was the Dr. Watson error when they tried to view the .jpg's on one of the machines).
Fortunately, now I can dump this back to the Windows admin here (the one who told me that my anti-virus system had failed to detect the "virus" in the first place) and have him wipe and reload their workstations.
:)