Are emoticons the electronic equivalent of dotting your "i" with a little heart?
Maybe that's a little harsh, but they are a current trend that you should be careful with. While I do use them from time to time in emails, I try not to use them too much. To use them all the time seems a little immature. Either that, or an indiciation that you need to do a better job wording your emails so that they aren't misunderstood.