One of the new features in iOS 5 is the ability to do some basic formatting in Mail on iPhone, iPad and iPod Touch. It’s easy to do, but unless you know where to look it’s unlikely that you’ll stumble upon it. When you are composing your message, simply select some text as if you were going to copy it (double tap a word then drag the edges to highlight the entire selection you want if needed). Next tap the triangle
pointing to the right in the popup menu. From there you’ll see basic formatting such as bold, italics, and underline.