Snopes posted another e-mail chain about Kerry. No surprise--it's fake. In the interest of fairness, there have been several about Bush--this, this, and this.
It's interesting about the scope of the claims. The first two about Bush center around a slip of the tongue (something possible for anybody) but the two recent ones about Kerry (as well as the one about IQs) throw a lot of facts at the reader that could easily be proven false.