§ Md. Election Law § 9-504(untitled)

(a) A voter may return a vote–by–mail ballot to a local board: (1) by mail; (2) in person during regular office hours; or (3) through a duly authorized agent in accordance with subsection (b) of this section. (b) (1) A voter may designate a duly authorized agent in accordance with § 9–307 of this title to return a vote–by–mail ballot to a local board during regular office hours. (2) Notwithstanding § 9–307(b)(4)(i) of this title, an agent is required only to: (i) witness the voter mark the ballot and place it in an envelope; and (ii) return the ballot to a local board. §9–505. (a) A vote–by–mail ballot is considered timely and may be counted if the ballot: (1) is returned in person to the office of a local board by the voter or the voter’s duly authorized agent no later than 8 p.m. on the day of a special election; or (2) (i) is received by mail by a local board no later than 10 a.m. on the second Friday after a special election; and (ii) was mailed on or before election day, as verified: 1. by a postmark; or 2. if the return envelope does not contain a postmark or the postmark is illegible, by the voter’s affidavit that the ballot was mailed on or before election day. (b) A vote–by–mail ballot that does not meet the requirements of subsection (a) of this section is not timely and may not be counted.