D.C. Mun. Regs. tit. 25-B, § 3403
3403.1 Proof of proper service may be made by certificate of service signed by the person making service or by admission of a return receipt, certificate of mailing, or a written acknowledgment signed by the licensee, dealer, the person operating a food processing operation without a license or dealer certification, or an authorized agent.
SOURCE: Final Rulemaking published at 56 DCR 5245 (July 3, 2009).