Minn. Stat. § 45.028
Subd. 1. Requirement.
Subd. 2. How made.
Service of process under this section may be made by leaving a copy of the process in the office of the commissioner, or by sending a copy of the process to the commissioner by certified mail, and is not effective unless: (1) the plaintiff, who may be the commissioner in an action or proceeding instituted by the commissioner, sends notice of the service and a copy of the process by certified mail to the defendant or respondent at the last known address; and (2) the plaintiff's affidavit of compliance is filed in the action or proceeding on or before the return day of the process, if any, or within further time as the court allows.