1. DON'T TYPE IN ALL CAPS. This is perceived as shouting.
2. Use emoticons (smileys) when trying to convey a tone of voice :-)
3. Limit line length to 65-70 characters across. Otherwise some e-mail programs will wrap the text at wrong points or not wrap it at all.
4. Consider carefully what you write; it's a permanent record and can be easily forwarded to others.
5. Write succinctly. Don't waste bandwidth. E-mail may be inexpensive to most, but not to all.
6. Don't attach large files (over 50K) without getting permission from your recipient first.
7. Don't attach files for posting to discussion groups.
8. Turn off e-mail formatting (non-ASCII) when posting to a discussion group.
9. Don't send entire web pages to a discussion group, just the URLs (http's).
10. When sending a web site address, always type it in the form of "http://…" because some e-mail programs will permit the user to click on a web address to go right there. Without the "http://" prefix these programs will not recognize it as such.
11. Don't blatantly promote your business by posting an advertisement to a discussion group, unless it is clearly an accepted use and you have cleared it with the moderator (if there is one) first. Otherwise, you are "spamming."
12. Write descriptive subject lines. Many busy people will only open messages with captivating subject lines. Think creatively.
13. Don't quote back an entire message when only responding to one or two points. Delete the excess and make a note at the very top before starting the quotes. Some e-mail programs will automatically set up to quote the original message when replying and put you at the end of that message. This is very annoying to your recipients.
14. When forwarding messages, put your comments at the top of the message.
15. Don't overuse acronyms like BTW (by the way) or IMHO (in my humble opinion). Not everyone is experienced with this jargon and they may not want to admit their confusion - possibly losing your point.
16. Do not forward personal e-mail to a discussion group without getting the author's permission first.

Read over your e-mail before you send it. Although e-mail is a more informal method of communication than writing a letter, be sure you make your points clear and concise. Use a spell checker if available.