E-mail has come of age, says Tim Sanders, author of The Likeability Factor and former Yahoo executive.

In fact, e-mail is now so mature that certain rules are not just etiquette - they're do or die.

Here's one example offered by Sanders.

"E-mail is for saying yes or maybe, or to exchange harmless information. If you use it to say no or to criticize, you've made a serious mistake. You should have done so in person or on the phone."

For more information about Tim Sanders and his ultra-modern business success formulas visit www.timsanders.com.