Mo. Rev. Stat. § 535.081
The right of a successor in title to recover rents pursuant to section 535.070 requires adequate and timely notice to the tenant. Except in counties of the first classification as determined pursuant to section 48.020, for the purposes of this section, "adequate and timely notice" means that the purchaser shall notify tenants in writing of the fact that title to the property has been transferred, and of the means of the transfer and the date of the transfer and the notice shall be attached to a copy of the deed which has been recorded. In counties of the first classification as determined pursuant to section 48.020, in lieu of a copy of the deed which has been recorded, the notice required by this section may be attached to a notarized affidavit executed by both the prior owner of the property and the successor in title, which notarized affidavit shall state that the property has been transferred to the successor in title and the date on which the transfer occurred.
§ 535.081, RSMo