Your letter should have a professional and informative tone, covering exactly why you're denying their rental application. If you email or write a letter, keep it clear, concise, and professional.Don't complain or criticize the landlord's decision. In this article, we'll talk you through what's included in a rental application denial letter and even give you a free template to use. With your tenants, send a quick email and just say, "Bob, thanks for submitting your application. In your letter, you should politely decline the applicant. You can always provide a letter of explanation to explain any negative rental issues, bad credit, or criminal history. 7. Download a customizable rental application rejection letter template for landlords or property managers to professionally notify applicants. A rental application denial letter, also known as an adverse action letter, is a formal document that a landlord or property manager sends to applicants.