49 C.F.R. § 1503.409 – Service of documents.

(a) General. This section governs service of documents required to be made under this part.
(b) Type of service. A person may serve documents by:
1. (1) Personal delivery;
2. (2) Mail, or
3. (3) Electronic mail or facsimile transmission, if consented to in writing by the person served, except that such service is not effective if the party making service receives credible information indicating that the attempted service did not reach the person to be served.
(c) If a party serves a pleading on another party during the course of hearing proceedings by electronic mail or facsimile transmission, the party making service must file with the Enforcement Docket Clerk a copy of the consent of the receiving party to accept such method of service.
(d) Date of service. The date of service will be:
1. (1) The date of personal delivery.
2. (2) If mailed, the mailing date stated on the certificate of service, the date shown on the postmark if there is no certificate of service, or other mailing date shown by other evidence if there is no certificate of service or postmark.
3. (3) If sent by electronic mail or facsimile transmission, the date of transmission.
(e) Valid service. A document served by mail or personal delivery that was properly addressed, was sent in accordance with this part, and that was returned, that was not claimed, or that was refused, is deemed to have been served in accordance with this part. The service will be considered valid as of the date and the time that the document was deposited with a contract or express messenger, the document was mailed, or personal delivery of the document was attempted and refused.
(f) Presumption of service. There will be a presumption of service where a party or a person, who customarily receives mail, or receives it in the ordinary course of business, at either the person's residence or the person's principal place of business, acknowledges receipt of the document.
(g) Additional time after service by mail. Whenever a party has a right or a duty to act or to make any response within a prescribed period after service by mail, or on a date certain after service by mail, 5 days will be added to the prescribed period.
(h) Service of documents filed with the Enforcement Docket. A person must serve a copy of any document filed with the Enforcement Docket on each party and the ALJ or the chief ALJ if no judge has been assigned to the proceeding at the time of filing. Service on a party's attorney of record or a party's designated representative is service on the party.
(i) Certificate of service. Each party must attach a certificate of service to any document tendered for filing with the Enforcement Docket Clerk. A certificate of service must consist of a statement, dated and signed by the person who effected service, of the name(s) of the person(s) served, and the method by which each person was served and the date that the service was made.
(j) Service by the ALJ. The ALJ must serve a copy of each document he or she issues including, but not limited to, notices of pre-hearing conferences and hearings, rulings on motions, decisions, and orders, upon each party to the proceedings.