Mich. Comp. Laws § 600.1951

Sec. 1951. Mailing under section 1947 shall be accomplished by complying with the following: (1) Enclosing a copy of the order as above described in a sealed envelope with first class postage fully prepaid addressed to the defendant at the address hereinbefore required, on which envelope there is listed a return address to which it can be returned in case delivery cannot be made. (2) Depositing the envelope and contents in the United States government mail.