Mo. Rev. Stat. § 521.320

The receiver shall forthwith give notice of his appointment to the persons indebted to the defendant. The notice shall be written or printed, and shall be served on each debtor, by a copy delivered to him, or left at his place of residence or business, or, if he resides in another county, by a copy deposited in the post office, and addressed to him at his place of residence; and from the date of such service and knowledge thereof, every such debtor shall stand liable, and shall account to the receiver for the amount of moneys and credits of the defendant in his hands, or due from him to the defendant.