Mo. Rev. Stat. § 472.445: Catalogue of electronic communications, disclosure to agent, when.

Unless otherwise ordered by the court, directed by the principal, or provided by a power of attorney, a custodian shall disclose to an agent with specific authority over digital assets or general authority to act on behalf of a principal a catalogue of electronic communications sent or received by the principal and digital assets, other than the content of electronic communications, of the principal if the agent gives the custodian:

(1) A written request for disclosure in physical or electronic form;

(2) An original or a copy of the power of attorney that gives the agent specific authority over digital assets or general authority to act on behalf of the principal;

(3) A certification by the agent, under penalty of perjury, that the power of attorney is in effect; and

(4) If requested by the custodian for the purpose of identifying the correct account of the correct user:

(a) A number, username, address, or other unique subscriber or account identifier assigned by the custodian to identify the principal's account; or

(b) Evidence linking the account to the principal.