Missouri Revised Statutes Title XXIX. Ownership and Conveyance of Property § 441.065. Abandonment of rental premises, when, procedure

(1) The landlord has a reasonable belief that the tenant has vacated the premises and intends not to return;

(2) The rent is due and has been unpaid for thirty days; and

(3) The landlord posts written notice on the premises and mails to the last known address of the tenant by both first class mail and certified mail, return receipt requested, a notice of the landlord's belief of abandonment. The notice shall include the following, where appropriate:

“The rent on this property has been due and unpaid for thirty consecutive days and the landlord believes that you have moved out and abandoned the property. The landlord may declare this property abandoned and remove your possessions from this unit and dispose of them unless you write to the landlord stating that you have not abandoned this unit within ten days of the landlord having both posted this notice on your door and mailing this notice to you. You should mail your statement by regular first class mail and, if you so choose, by certified mail, return receipt requested, to this address ․․․․․․․․․․ (here insert landlord's name and street address)”; and

(4) The tenant fails to either pay rent or respond in writing to the landlord's notice within ten days after both the date of the posting and deposit of such notice by either first class mail or certified mail, return receipt requested, stating the tenant's intention not to abandon the premises.