At present, e-mail has become the default communication tool for business because of sending an e-mail is simple, cheap and quick.
It can present bad impressions if you don't write it properly.
You can learn how to use e-mail more effectively.
First, you should know your audience, corresponding with customers probably requires a more formal tone than emailing colleagues.
Next, proof and read your e-mail, check the spelling and grammar, re-reading before sending.