Tips for Effective E-mail:
Think before you write. Just because you could send information faster than ever before, it does not mean which you should send it. Analyse your readers to make certain which you are sending a message that will be both clear and useful.
Note that you can always deny that you said it. But if you write it, you might be held accountable for many moons. You might be surprised to search where your message may end up.
Keep your message concise. Note that the view screen in most e-mail programs shows only approximately one half of a hard-copy page. Save longer messages & formal reports for attachments. Instead, do not keep your message so short in which the reader has no idea what you are talking about. Involve at least a summary (action or information?) within the first paragraph of your message.
Note that e-mail is not necessarily confidential. A few companies will retain the right to monitor employees' messages. Do not send anything you would not be comfortable seeing published in your company's newsletter (or your community's newspaper).
Do not attempt to "discipline" your readers. It is unprofessional to lose control in person
"To do so in writing usually just makes the situation worse."
Do not "spam" your readers. Do not send them unnecessary or frivolous messages. Soon, they will quit opening any message from you.