Mo. Rev. Stat. § 137.135: Duplicate list to be left if made during absence of owner.

Whenever an assessment of property is made in the absence of the owner thereof, a duplicate list of such assessment shall be left, at the time of assessment, with some other member of the family not less than fifteen years of age, or with whoever may be in charge of such property. If the owner of the property is a nonresident, and neither he nor his agent is present when the assessment is made, a duplicate of the assessment shall be mailed by the assessor to the owner at his last address, if known.