Section 6-421 - Service of complaints, orders, etc(a) Any complaint, corrective order, notice, or other instrument issued by the Department under this subtitle may be served on the person to whom it is directed in accordance with § 1-204 of this article.(b) If service is made by certified mail, return receipt requested, bearing a postmark from the United States Postal Service, the person who mails the document shall file with the Department verified proof of mailing.(c) Any notice that requires filing of a report, attendance at a hearing, or both, shall be served at least 10 days before the earlier of:(1) The time set for the hearing, if any; or(2) The time set for the filing of the report, if any.