How To Write An Inquiry Letter . If the inquiry concerns several topics at once, then it should be divided into points or sections. When writing an email for business inquiries, keep your email subject line short, sweet, and straight to the point. 10 Sample Inquiry Letters Examples. Format and How To Write Inquiry from www.aplustopper.com How to write a letter of inquiry. Once you have determined who to address your job inquiry letter to, you are ready to. Add the subject of the letter precisely to give some idea of what will be discussed in the letter.