Mo. Rev. Stat. § 392.170
Every telephone or telegraph company now organized under the laws of this state, and every telephone or telegraph company now organized, or which may hereafter be organized under the laws of any other state or territory, and doing business in this state, shall be liable for special damages occasioned by the failure or negligence of their operators or servants in receiving, copying, transmitting or delivering dispatches; and for the disclosure of any of the contents of any private dispatches to any person other than to him to whom it was addressed, or to his agent, they shall be liable to the sender of the dispatch, and to the person to whom it was addressed, in the sum of fifty dollars to each, recoverable by any action before a magistrate, and for all special damages in addition thereto.
§ 392.170, RSMo