(a) The Recorder shall cause a notice of hearing and a copy of the petition to be transmitted to the postmaster at any office of address of the respondent in which the respondent is doing business, which shall be delivered to the respondent or respondent's agent by said postmaster or the postmaster's designee. A receipt acknowledging delivery of the notice shall be secured from the respondent or respondent's agent and forwarded to the Recorder, to become a part of the official record.

(b) If, after 5 days, the postmaster or the postmaster's designee, can find no person to accept service of the notice of hearing and petition pursuant to paragraph (a) of this section, the notice and copy of the petition may be delivered in the usual manner as other mail addressed to the respondent. A statement, showing the time and place of delivery, signed by the postal employee who delivered the notice of hearing and petition shall be forwarded to the Recorder and such statement shall constitute evidence of service.