D.C. Mun. Regs. tit. 10, r. 10-C3007
Any paper required to be served upon a party shall be served upon the party or upon the representative designated by the party or by law to receive service of papers. When a party has appeared by attorney or other representative, service shall be made upon the attorney or representative of record.
Service may be made by personal or overnight delivery, U.S. mail, facsimile, electronic mail, or as otherwise authorized by law. Where there are numerous parties to a proceeding, the Mayor's Agent may make special provisions at the proceeding regarding the service of papers.
Service by personal delivery upon a party is complete on handing the paper to the person, or leaving it at the person's office with a clerk or other person in charge, or if there is no one in charge, leaving it in a conspicuous place in that office. If the office is closed or the person to be served has no office, service is complete by leaving the paper at the person's usual place of residence with a resident or employee of suitable age and discretion.
Service by mail upon a party is complete on deposit in the United States mail, properly stamped and addressed.
Service by overnight delivery is complete on deposit with the delivery company, properly addressed and with the charges prepaid.
Service by facsimile is complete when telecopied with the proper telephone number of the intended recipient's telecopier.
Service by electronic mail is complete when transmitted electronically, properly addressed to the attention of the intended recipient, with proper e-mail address.
Proof of service, stating the name and address of the person on whom served and the manner and date of service, shall be shown for each document filed, and may be made by any of the following ways:
D.C. Mun. Regs. tit. 10, r. 10-C3007