Don’t underestimate the importance of a clear and concise subject line. This may mean the difference between your email being treated as spam, deleted or designated low priority. Including a clear subject line can also help the recipient find your email in future.
Remember that an email is effectively a letter. Make sure you include a polite greeting and a clear sign-off. It is also more professional to setup an email signature with your company details. Sending an email with no greeting or sign-off can seem brusque to the point of rudeness.
Set up a signature in your corporate colours, or with a personal image rather than using the stationery built into your email programme. These formatted styles and backgrounds can wreak havoc when the recipient is trying to reply to you or forward your email. They are generally disliked and force the recipient to muck about with formatting settings for five minutes before sending their own email.