Tone and style for email

Here's some email advice from a pro:

To determine the appropriate style and tone, consider three things:

1. your relationship to the reader;
2. the subject of the e-mail; and
3. the purpose of the e-mail.

First: Who are you writing to, and how well do you know them? How would you talk to them on the phone or face-to-face?

Second: Is the subject casual and trivial, or is it a serious business issue?

Third: Will your readers review the message and delete it? Will the e-mail be filed? Will it possibly be printed out for distribution at a client meeting? Will it serve as evidence in a legal proceeding?

--Dianna Booher, E-Writing: 21st-Century Tools for Effective Communication 32 (Pocket Books 2001).