e-mail etiquette: 12 things you SHOULD know !

1. Be informal.
2. Keep messages brief and to the point.
3. Use sentence case. USING ALL CAPITAL LETTERS LOOKS AS IF YOU'RE SHOUTING.
4. Use the blind copy and courtesy copy appropriately. Don't use BCC to keep others from seeing who you copied;
5. Don't use e-mail as an excuse to avoid personal contact. Don't forget the value of face-to-face or even voice-to-voice communication. Remember that e-mail isn't private.
6. Remember that e-mail can be forwarded,
7. Be sparing with group e-mail.
8. Use the subject field to indicate content and purpose. Don't just say, "Hi!" or "From Laura." Agree on acronyms to use that quickly identify actions.
9. Don't send chain letters, virus warnings, or junk mail.
10. Remember that your tone can't be heard in e-mail.
11. Use a signature that includes contact information. To ensure that people know who you are, include a signature that has your contact information, including your mailing address, Web site, and phone numbers.
12. Summarize long discussions.

Source: http://office.microsoft.com/en-us/outlook/HA012054101033.aspx