D.C. Code § 6-703.07
Any notice required by §§ 6-703.03 to 6-703.09 shall be deemed to have been served if delivered to the person to be notified or left with any adult person at the usual residence or place of business of the person to be notified in the District of Columbia, or, if no such residence or place of business can be found in said District of Columbia by reasonable search, if left with any adult person at the office of any agent of the person to be notified, provided such agent has any authority or duty with reference to the building to which said notice relates, or, if no such office can be found in said District, by reasonable search, if forwarded by registered mail or by certified mail to the last known address of the person to be notified and not returned by the post office authorities, or, if no address be known or can by reasonable diligence be ascertained, or if any notice forwarded as authorized by the preceding clause of this section be returned by the post office authorities, if published on 10 consecutive days in a daily newspaper published in the District of Columbia, or, if by reason of an outstanding unrecorded transfer of title, the name of the owner in fact cannot be ascertained beyond a reasonable doubt, if served on the owner of record in the manner hereinbefore provided or delivered to the agent, trustee, executor, or other legal representative of the estate of such person. Any notice to a corporation shall, for the purposes of §§ 6-703.03 to 6-703.09, be deemed to have been served on such corporation if served on the president, secretary, treasurer, general manager, or any principal officer of such corporation in the manner hereinbefore provided for the services of notices on natural persons holding property in their own right, or if no such officer can be found in said District by reasonable search, then by publication for 10 consecutive days in a daily newspaper published in the District of Columbia, and notice to a foreign corporation shall, for the purposes of §§ 6-703.03 to 6-703.09, be deemed to have been served if served on any agent of such corporation personally or if left with any person of suitable age and discretion residing at the usual residence or employed at the usual place of business of such agent in the District of Columbia, or if published on 10 consecutive days in a daily newspaper published in the District of Columbia.
D.C. Code § 6-703.07
Documentary evidence, prima facie evidence of delivery, certified mail return receipts, see § 14-506 . .