Today's key (June 12th) has been won.

Deathsless is the winner of today's free key.  He was the first (and only one) to email us the winning code from today.  This code was posted around 9:30AM EST and it took over 1 hour for it to be found, the longest yet.  It was hidden in the spreadsheet under the "Notes" tool-tips.  In order to see today's code one would have to mouse-over the Notes section of the spreadsheet and it would reveal the code.  It read "the text that you want to email us fast is 'supply and demand'".  Congratulations to Deathsless for winning today's key.  Good luck to everyone for tomorrow's free key (details here).