25 C.F.R. § 580.4 – How do I effect service?

(a) An appellant shall serve its notice of appeal on the Commission at the address indicated in the decision or notice that is the subject of the appeal.
(b) Copies of the notice of appeal shall be filed personally or by registered or certified mail, return receipt requested. All subsequent documents shall be served personally, by facsimile, by email to an address designated by a Commission employee, or by first class mail. In matters where a hearing has been requested, all filings shall be made with the Commission until a presiding official is designated and the parties are so notified, after which all filings shall be made with the presiding official.
(c) All documents filed after the notice of appeal shall be served on the Commission and copies concurrently served on all parties, intervenors, or limited participants.
(d) Service of copies of all documents is complete at the time of personal service or, if service is made by mail, facsimile, or email, upon transmittal.
(e) When a representative (including an attorney) has entered an appearance for a party, limited participant, or intervenor in a proceeding initiated under any provision of parts 582 through 585 of this subchapter, service thereafter shall be made upon the representative.
(f) The Commission may extend the time for filing or serving any document, except a notice of appeal.
1. (1) A request for an extension of time must be filed within the time originally allowed for filing.
2. (2) For good cause, the Commission may grant an extension of time on its own motion.
(g) Rules governing service of documents by the Chair or Commission are governed by part 519 of this chapter.