19 C.F.R. § 210.54
Notwithstanding the provisions of § 210.11 regarding service of the complaint by the Commission upon institution of an investigation, on the day the complainant files a complaint and motion for temporary relief, if any, with the Commission (see § 210.8(a)(1) and (a)(2) of subpart B of this part), the complainant must serve non-confidential copies of both documents (as well as non-confidential copies of all materials or documents attached thereto) on all proposed respondents and on the embassy in Washington, DC of the country in which each proposed respondent is located as indicated in the Complaint. If a complainant files any supplemental information with the Commission prior to institution, nonconfidential copies of that supplemental information must be served on all proposed respondents and on the embassy in Washington, DC of the country in which each proposed respondent is located as indicated in the complaint. The complaint, motion, and supplemental information, if any, shall be served by messenger, overnight delivery, or equivalent means. A signed certificate of service must accompany the complaint and motion for temporary relief. If the certificate does not accompany the complaint and the motion, the Secretary shall not accept the complaint or the motion and shall promptly notify the submitter. Actual proof of service on each respondent and embassy (e.g., certified mail return receipts, messenger, or overnight delivery receipts, or other proof of delivery)-or proof of a serious but unsuccessful effort to make such service-must be filed within 10 days after the filing of the complaint and motion. If the requirements of this section are not satisfied, the Commission may extend its 35-day deadline under § 210.58 for determining whether to provisionally accept the motion for temporary relief and institute an investigation on the basis of the complaint.
19 C.F.R. §210.54