Md. Code, State Government § 10–209

(a) Where a licensing statute provides for service other than by regular mail, notice under this subtitle may be sent by regular mail to the address of record of a person holding a license issued by the agency if:

(1) the person is required by law to advise the agency of the address; and

(2) the agency has been unsuccessful in giving notice in the manner otherwise provided by the licensing statute.

(b) Upon a showing that the person neither knew nor had reasonable opportunity to know of the fact of service, a person served by regular mail under subsection (a) of this section shall be granted a hearing.

(c) A person holding a license shall be deemed to have had a reasonable opportunity to know of the fact of service if:

(1) the person is required by law to notify the agency of a change of address within a specified period of time;

(2) the person failed to notify the agency in accordance with the law;

(3) the agency or the Office mailed the notice to the address of record; and

(4) the agency did not have actual notice of the change of address prior to service.