Mich. Comp. Laws § 750.539
Divulging contents of messages-Any person connected with a telegraph, telephone or messenger company, incorporated or unincorporated, operating a line of telegraph or telephone, or engaged in the business of receiving and delivering messages in this state, in any capacity, who wilfully divulges the contents or the nature of the contents of a communication entrusted to him for transmission or delivery, or who wilfully refuses or neglects to transmit or deliver the same, or who wilfully delays the transmission or delivery of the same, or who wilfully forges the name of the receiver to any receipt for any such message or communication or article of value entrusted to him by such company, with a view to injure, deceive or defraud the sender or intended receiver thereof, or any such telephone, telegraph or messenger company or to benefit himself or any other person, shall be guilty of a misdemeanor.
MCL 750.539