By the Commission
(a) By the Commission. Except when service by another method shall be specifically ordered by the Commission, the service of a process or other document of the Commission shall be served by anyone duly authorized by the Commission and be effected (1) By mailing, delivering, or serving by electronic means a copy of the document to the person to be served, to a member of the partnership to be served, to the president, secretary, other executive officer, or member of the board of directors of the corporation, association, or other organization to be served, or, if an attorney represents any of the above before the Commission, by mailing, delivering, or serving by electronic means a copy to such attorney; or (2) By leaving a copy thereof at the principal office of such person, partnership, corporation, association, or other organization, or, if an attorney represents any of the above before the Commission, by leaving a copy at the office of such attorney. (3) By using an express delivery service to send a copy of the document to the principal office of such person, partnership, corporation, association, or other organization, or, if an attorney represents any of the above before the Commission, by serving the attorney by express delivery. (4) When service is by mail, it is complete upon mailing of the document. When service is by an express service, service is complete upon submitting the document to the express delivery service or depositing it in the appropriate container for pick-up by the express delivery service. When service is by electronic means, service is complete upon transmission of a notification that the document has been placed in an appropriate repository for retrieval by the person, organization, representative, or attorney being served, unless the Commission is notified that the notification was not received by the party served.