Make the subject line specific. Think of the many messages you're received with the generic subject line, "Hi" or "Just for you."

Don’t forward messages with three pages of mail-to information before they get to the content. In the message you forward, delete the extraneous information such as all the "Memo to," subject, addresses, and date lines.

When replying to a question, copy only the question into your e-mail, then provide your response. You needn't hit reply automatically, but don't send a bare message that only reads, "Yes." It's too blunt and confuses the reader.

Address and sign your e-mails. Although this is included in the To and From sections, remember that you’re communicating with a person, not a computer.

DON'T TYPE IN ALL CAPS. TOO INTENSE, and you appear too lazy to type properly. This is still a written medium. Follow standard writing guidelines as a professional courtesy.

(Business Etiquette refference)