One has to wonder how many people actually print emails - and how much of a difference this will really make. I print maybe 4 or 5 emails a YEAR. I don't think I'm unusual in that either.
That was my first thought as well. I can't even remember the last email I printed.
However, I do have a few friends who print everything -- and I do mean everything. Every email. Every web page article. Every cartoon. Everything. I'm guessing they kill a forest a year between them.
And if I'm going to print something -- I'll print it in a font I find readable and enjoyable, not a font that saves a drop or two of ink.