Emails that pass through it. Echelon is believed to largely be a satellite telecommunications listening device. They say that it also listens on telco trunks, but mainly listening to voice transmissions. Now is it possible that it monitors specific internet pipes into and out of a country - sure. However the logistics and such behind monitoring every US based ISP for example make it pretty darn impractical. There is absolutely no way in my mind that they monitor all the emails sent around the US. Too many ISPs would speak up and it's not like there is a central backbone that ALL internet traffic goes across. The only time you get that is on connections in and out of a country.

So my original point stands - educated people don't wear tinfoil hats.