Md. Code, Bus. Reg. § 16.7-204.1

(a) (1) A retail licensee or vape shop vendor shall post a sign in a location that is clearly visible to the consumer that states: “No person under the age of 21 may be sold tobacco products”. (2) The sign required under paragraph (1) of this subsection shall be written in letters at least one–half inch high. (b) (1) A retail licensee or vape shop vendor may not sell electronic smoking devices to an individual unless the retail licensee or vape shop vendor verifies, in accordance with paragraph (2) of this subsection, that the individual is at least 21 years old. (2) Except as provided in paragraph (3) of this subsection, a retail licensee or vape shop vendor may verify an individual’s age only: (i) by means of a government–issued photo identification containing the individual’s date of birth; and (ii) in a direct face–to–face exchange without the assistance of any electronic or mechanical device. (3) A licensed retailer or vape shop vendor is not required to verify the age of an individual at least 30 years old.