1. Be short and to the point.
Do not make an e-mail longer than it needs to be. Remember that if its to long it might confuse your person who your sending the email to. And they might not understand what the email means.
2. Use proper grammar and spelling
If you don't use proper use of grammar and spelling your email might be confusing and hard to read. They may not get the point of the email
3. Do not attach un needed files
If you attach un wanted files it might make your reader confused. And spread unwanted visitors known as virus's.
4. Do not type in ALL CAPITALS!
IF YOU WRITE IN CAPITALS IT SEEMS AS IF YOU ARE SHOUTING. This can be highly annoying and might trigger an unwanted response. And it is considered to be rude.
5. Read your email before you send it.
If you don't reread your message you may have unwanted mistakes that couls have easily been fixed. Like punctuation and spelling errors, that make the email harder to read.