There are certain professional standards expected for e-mail use. Here are some things to keep in mind regarding professional e-mail conduct:
1) Be informal, not sloppy.
Your colleagues may use commonly accepted abbreviations in e-mail, but when communicating with external customers, everyone should follow standard writing protocol. Your e-mail message reflects you and your company, so traditional spelling, grammar, and punctuation rules apply.
2) Keep messages brief and to the point.
Just because your writing is grammatically correct does not mean that it has to be long. Nothing is more frustrating than wading through an e-mail message that is twice as long as necessary. Concentrate on one subject per message whenever possible.
3) Use sentence case.
USING ALL CAPITAL LETTERS LOOKS AS IF YOU'RE SHOUTING. Using all lowercase letters looks lazy. For emphasis, use asterisks or bold formatting to emphasize important words. Do not, however, use a lot of colors or graphics embedded in your message, because not everyone uses an e-mail program that can display them.
4) Use the blind copy and courtesy copy appropriately.
Don't use BCC to keep others from seeing who you copied; it shows confidence when you directly CC anyone receiving a copy. Do use BCC, however, when sending to a large distribution list, so recipients won't have to see a huge list of names. Be cautious with your use of CC; overuse simply clutters inboxes. Copy only people who are directly involved.