Read this!!!!
The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) - Joel on Software
You have control over all areas of sending this email, is the character encoding the same in your web site as in your email???
Really, you shouldn't need any special functions like that, unless you want to convert & to &.
Those functions are intended for when you don't have control over the input/output encodings!!!!!