Maryland Code, Transportation § 12-114

(a) Unless another method for giving notice is specifically required, the Administration shall give any notice that it is required or authorized to give under the Maryland Vehicle Law  1 or any other law, either:

(b) If notice is given by mail, the notice is effective at the end of the fifth day after its deposit in the mail.

(c) Proof that notice has been given may be made by the certificate of any officer or employee of the Administration or the affidavit of any adult, naming the person to whom the notice was given and stating the time, place, and manner of giving the notice.