California Code, Probate Code - PROB § 873

(a) A user may use an online tool to direct the custodian to disclose to a designated recipient or not disclose some or all of the user's digital assets, including the content of electronic communications. If the online tool allows the user to modify or delete a direction at all times, a direction regarding disclosure using an online tool overrides a contrary direction by the user in a will, trust, power of attorney, or other record.

(b) If a user has not used an online tool to give direction under subdivision (a) or if a custodian has not provided an online tool, a user may allow or prohibit in a will, trust, power of attorney, or other record the disclosure to a fiduciary of some or all of the user's digital assets, including the contents of electronic communications sent or received by the user.

(c) A user's direction under subdivision (a) or (b) overrides a contrary provision in a terms-of-service agreement.