Section 13. Any person notified to appear before the municipal hearing officer, as provided herein may, without waiving the right to a hearing provided by this chapter and without waiving judicial review as provided in section 14 of chapter 30A, challenge the validity of the violation notice and receive a review and disposition of the violation from the municipal hearing officer by mail. The alleged violator may, upon receipt of the notice to appear, send a signed statement of objections to the violation notice as well as signed statements from witnesses, police officers, government officials and other relevant parties. Photographs, diagrams, maps and other documents may also be sent with the statements. Any statements or materials sent to the municipal hearing officer for review shall have attached the person's name and complete address as well as the ticket number and the date of the violation. The municipal hearing officer shall, within 21 days after receipt of such material, review the material and dismiss or uphold the violation and notify the alleged violator by mail of the disposition of the hearing. If the outcome of the hearing is against the alleged violator, the municipal hearing officer shall explain the reasons for the outcome on the notice. Such review and disposition conducted by mail shall be informal, the rules of evidence shall not apply and the decision of the municipal hearing officer shall be final, subject to any hearing provisions provided by this chapter or to judicial review as provided in said section 14 of said chapter 30A.