The speakerphone became max volume and the volume slider became unresponsive.
i had to open up another media player and play music to get the volume slider to work again
I really like this idea for uniquely identifying emails. Our shop had been messing with something similar, but had trouble bridge the gap between the lay people and the technical minded people.
There's also Vol 2, which is a PDF/A document that also parses as text/gemini: http://lab6.com/2
The last one has interesting discussion on the future of information archiving.