Mo. Rev. Stat. § 534.345: Notice of default judgment in eviction proceeding must be sent to defaulting party.

In an action pursuant to chapter 441, chapter 524, or this chapter, the court in entering a judgment for possession of the premises shall, if the defendant defaults, send a notice to the party ordered to relinquish possession that a judgment for possession of the premises has been entered against said party, and said party must vacate the premises when the judgment is final.