Mont. Code Ann. § 77-3-104

Upon the approval of an application for a prospecting permit or a mining lease under this part, the department shall promptly give written notice, by ordinary mail, to the permittee or lessee and to any holder of an agricultural or grazing lease embracing the same land or to any holder of a certificate of purchase or patent embracing the same land. The notice must be addressed to the permittee, mining lessee, agricultural or grazing lessee, purchaser, or patentee at the person's last-known post-office address.