If you write the English language with a language that is not the official view of any other company might make an overview of the company, damage to the company that you are not a professional.
If you write the English language is not official. Other companies may see an overview of your losses. You will see that the company is not professional.
If you write with English language casual may make other companies look at the whole of the companies you damage. Be that your company is not professional.