N.Y. Comp. Codes R. & Regs. tit. 11, § 301.4 – Unauthorized insurers: doing an insurance business.

(a) In connection with a purchasing group or a member of such group, an unauthorized insurer shall not do any act that would constitute the doing of an insurance business in this State.
(b) Except to the extent specifically permitted under section 1101 of the Insurance Law, the delivery in this State by mail or otherwise of any liability insurance policy by an unauthorized insurer to a purchasing group or a member of such group is prohibited.
(c) Except to the extent specifically permitted under section 1101 of the Insurance Law, an unauthorized insurer is doing an insurance business in this State if, acting on behalf of such unauthorized insurer:
1. (1) any person, firm, association or corporation in this State delivers a liability insurance policy to a purchasing group or a member of such group; or
2. (2) any purchasing group, its representative or any other person, firm, association or corporation in this State delivers a liability insurance policy to a member of such group.