After reading a message, the reader should be able to determine (without a doubt) the purpose of the correspondence.  Clear messages reflect clear thinking.  Each sentence should have one thought and each paragraph one purpose.  Business correspondence is not the place to impress a person with your vocabulary – your aim is to get your purpose across in a simple, concise manner.  If a short, easily understood word is available, use it.  Your words should express rather than impress!