I get irritated when some people proudly bragged that they work in a so-called multinational company yet sending me official documents with typo errors! I suggest you to check whether people like us who work in a local company use bad English! I still can accept it if they use bad grammar in the email. However, please do not send unchecked files to your dear customers! I am not saying I have a perfect English (written & oral), but I try not to let the obvious one, i.e. spelling mistake, get caught by my boss.
Read about an English teacher <here>