Mich. Comp. Laws § 554.612

Sec. 12. If a landlord claims damages to a rental unit and gives notice of damages as required, the tenant upon receipt of the list of damages shall respond by ordinary mail to the address provided by the landlord as required by section 3 within 7 days, indicating in detail his agreement or disagreement to the damage charges listed. For the purposes of this section the date of mailing shall be considered the date of the tenant's response.