12 C.F.R. § 1102.25 – Service.

(a) Methods; appearing party. A serving party, who has made an appearance under § 1102.22 of this subpart, shall use one or more of the following methods of service:
1. (1) Personal service;
2. (2) Delivering the papers to a reliable commercial courier service, overnight delivery service, or to the U.S. Post Office for Express Mail delivery; and
3. (3) Mailing the papers by first class, registered, or certified mail.
(b) Methods; non-appearing party. If a party has not appeared in the proceeding in accordance with § 1102.22 of this subpart, the ASC or any other party shall make service by any of the following methods:
1. (1) By personal service;
2. (2) By delivery to a person of suitable age and discretion at the party's last known address;
3. (3) By registered or certified mail addressed to the party's last known address; or
4. (4) By any other manner reasonably calculated to give actual notice.
(c) By the Subcommittee. All papers required to be served by the ASC shall be served by the Secretary unless some other person shall be designated for such purpose by the ASC.
(d) By the respondent. All papers filed in a proceeding under this subpart shall be served by a respondent on the Secretary and each party's attorney, or, if any party is not so represented, then upon such party. Such service may be made by any of the appropriate methods specified in paragraphs (a) and (b) of this section.