I think any communication changes its tone depending on the mood and importance of the conversation. E-mail also falls in this category. Though it is different than letters and IMs, we are only learning this medium's strengths and weaknesses. All communication can suffer misunderstanding, beause you can never actually predict what goes on in other person's mind. Even though many generations are used to talking, there is no guarantee that what you speak gets conveyed, so it is with e-mail. There are definitely invisible cues in e-mails like in body language and you have to train yourself to "Read" those. Sometimes e-mail works in your favor by not having to engage yourself physically in the conversation, especially for people who are better at writing than talking or social skills.