1720.170—Service.
Notices, orders, processes, determinations and other documents required or permitted under these rules may be served as follows:
(a) Upon the Secretary.
By personal delivery at the office, or by registered or certified mail addressed to the office of any of the following officials in the Office of Interstate Land Sales Registration: Administrator; Associate Administrator; Director, Office of Interstate Land Sales Registration: Provided, however, That during the pendency of a proceeding before the Secretary all pleadings, motions, notices or other documents shall be served in accordance with the terms of § 1720.160.
(b) Upon any other person.
By delivery of a copy of the documents to the person to be served wherever the person may be found, or by leaving such copy at the person's office or place of business with a person apparently in charge thereof, or, if there is no one in charge or if the office is closed or if the person has no office, by leaving a copy at the person's residence with some person of suitable age and discretion then residing therein, or sending a copy by registered or certified mail, return receipt requested, addressed to the person at the person's last known residence, or at the person's last known principal office or place of business. If the address of the residence, principal office, or place of business is unknown and cannot with due diligence be ascertained, service may be made by mail to any office at which the person to be served is known to be employed or by publication in the Federal Register.
(c) Service on corporations, partnerships, associations, other entities.
Service may be made upon any corporation, partnership, business association or other entity by serving any officer, director, partner, trustee, agent for service or managing agent thereof. A managing agent, within the meaning of this subsection, is an agent having the principal managerial responsibility in connection with the regular operation of a distinct office or activity of the enterprise.
(d) Service through attorney.
When a person other than the Secretary and the Secretary's staff shall have appeared of record in a proceeding, generally or specially, by attorney, all subsequent services of notices, orders, processes, and other documents in connection with such proceeding may be made upon such person by serving the attorney, except that subpoenas and other orders by which such person may be brought in contempt shall be served upon the person by one of the methods described in paragraphs (b) and (c) of this section. In any case, a copy of any document served on a client shall be sent to any attorney who has entered an appearance for that client. In such situations, it shall be sufficient proof of service to show that either the client or the attorney has received a copy of the document.
(e) Proof of service.
Proof of service shall not be required unless the fact of service is reasonably put in issue by appropriate motion or objection on the part of the person allegedly served or other party. In such cases, service may be established by written admission signed by or on behalf of the person to be served, or may be established prima facie by affidavit or certificate of service or mailing, as appropriate. When service is by registered or certified mail, it is complete upon delivery of the document by the post office.