39 CFR § 952.8 - Service.
(a) Where Respondent's mailing address is within the United States, the Recorder shall cause a notice of docketing and answer due date (the “Notice”), a copy of these rules of practice, and a copy of the complaint to be transmitted to Complainant who shall serve those documents upon Respondent or his or her agent by certified mail, return receipt requested. Service shall be complete upon mailing. A receipt acknowledging delivery of the notice shall be secured from Respondent or his or her agent and forwarded to the Recorder, U.S. Postal Service, 2101 Wilson Boulevard, Suite 600, Arlington, VA 22201-3078, to become a part of the official record. In the absence of a receipt, Complainant shall file an Affidavit of Service, along with returned undelivered mail, or other appropriate evidence of service, with the Recorder. In the alternative Complainant may, in its discretion, effectuate service by hand on Respondent and file an Affidavit of Service with the Recorder.
(b) Where the only address against which Complainant seeks relief is outside the United States, a copy of the complaint, the tentative decision, and a copy of these rules of practice shall be sent by international mail, return receipt requested, by the Recorder to the address cited in the complaint. A written statement by the Recorder noting the time and place of mailing shall be accepted as evidence of service in the event a signed return receipt is not returned to the Recorder.