You could only make about five legible copies. So you thought good and hard about who you wanted to send those five copies to. Today, it's as easy to copy practically anyone on your mail as it is not to. And we sometimes find ourselves copying people almost out of habit. In general, this is rude.
People have less time than ever today, precisely because they have so much informati on to absorb.
Before you copy people on your messages, ask yourself whether they really need to know. If the answer is no, don't waste their time. If the answer is maybe, think twice before you hit the send key.