Mich. Comp. Laws § 445.2503: Unsolicited commercial e-mail; requirements.

Sec. 3.

A person who intentionally sends or causes to be sent an unsolicited commercial e-mail through an e-mail service provider that the sender knew or should have known is located in this state or to an e-mail address that the sender knew or should have known is held by a resident of this state shall do all of the following:

Include in the e-mail subject line "ADV:" as the first 4 characters.

Conspicuously state in the e-mail all of the following:

The sender's legal name.

The sender's correct street address.

The sender's valid internet domain name.

The sender's valid return e-mail address.

Establish a toll-free telephone number, a valid sender-operated return e-mail address, or another easy-to-use electronic method that the recipient of the commercial e-mail message may call or access by e-mail or other electronic means to notify the sender not to transmit by e-mail any further unsolicited commercial e-mail messages. The notification process may include the ability for the commercial e-mail messages recipient to direct the sender to transmit or not transmit particular commercial e-mail messages based upon products, services, divisions, organizations, companies, or other selections of the recipient's choice. An unsolicited commercial e-mail message shall include, in print as large as the print used for the majority of the e-mail message, a statement informing the recipient of a toll-free telephone number that the recipient may call, or a valid return address to which the recipient may write or access by e-mail, notifying the sender not to transmit to the recipient any further commercial e-mail messages.

Conspicuously provide in the text of the commercial e-mail, in print as large as the print used for the majority of the e-mail, a notice that informs the recipient that the recipient may conveniently and at no cost be excluded from future commercial e-mail from the sender as provided under subdivision (c).