Except as otherwise provided in subsection (b) of this section, a real estate broker, an associate real estate broker, or a real estate salesperson may not pay or offer to pay a commission to a lawyer simply for the referral of a person as a possible party to a residential real estate transaction. A real estate broker, an associate real estate broker, or a real estate salesperson may not solicit referral business from lawyers by a mass solicitation that offers to pay fees or commissions to the lawyers. Subsection (a)(1) of this section does not apply to payments or offers of payments to lawyers who hold a real estate broker license under this title or are otherwise entitled to a commission. Other than the commissions expressly prohibited, subsection (a) of this section does not prohibit the payment or the offer of a payment of a commission by a real estate broker, an associate real estate broker, or a real estate salesperson to a lawyer for any service that relates to a real estate transaction.