10 Tips on How to Write a Business Email in English

This is a good read and tips:

Writing and receiving emails has become an inevitable part of everyday life, both in private and business correspondence. When writing an email to your family or friends, you may be as casual as you want. But wait, are you sure you can write a proper business letter to your boss or a client? There are some business email etiquette rules and that everyone is required to follow, even if you are a non-native English speaker.

Read more: http://www.egida.rs/10-tips-on-how-to-write-a-business-email-in-english/

I also came across with this article as well: http://tips-for-writing.blogspot.com/2006/05/writing-tip-1-give-your-reader-some.html