I seem to encounter many email fouls in my business happenings, having to couch employees and colleagues on proper email etiquette which often seems to me as obvious, yet to others a yet to be refined skill. I even observe these problems in senior executives from time to time – so writing a quality (and successful) email with proper etiquette doesn’t just challenge new employees coming out of school. In fact, I’m not sure etiquette is taught at the undergraduate level with the exception of a few select/niche programs.

Here’s a great article written by Tim Berry at SmallBizTrends.com:
http://smallbiztrends.com/2011/01/3-simple-rules-for-better-business-emails.html

Pay close attention to points #6, 8 and 9. These are rarely recognized by inexperienced staff. As a result, you should be defensive when sending emails to staff that disregard these points. In other words, be careful what you send these people as they may send your mail to others or infer from it incorrectly.