D.C. Mun. Regs. tit. 14, r. 14-1204
Each apartment entrance door shall be distinctively numbered or lettered and all other rooms in the apartment buildings shall be distinctively identified.
The provisions of this section shall not apply to rooms in individual apartments.
The owner of each apartment house shall maintain and provide the tenants of each apartment the use of a secure mail receptacle which has been approved by the United States Postal Service.
Each receptacle, other than those in an apartment house that has twenty-four (24) hour-a-day desk clerk service, is required to have a lock that will enable it to be secured and the owner shall provide each tenant with a key to the lock.
Installation, security specifications, and maintenance of mail receptacles shall be consistent with the requirements of postal service laws and regulations.
The owner shall be responsible for the proper installation of mail receptacles, and shall maintain the same in safe and good working condition.
In the event of disrepair, the owner shall have a reasonable time (not to exceed seven (7) working days) to repair mail receptacles.
D.C. Mun. Regs. tit. 14, r. 14-1204