Section 38a-273 - (Formerly Sec. 38-266). Secretary of the State as agent for service of process in proceedings by the state or commissioner. Judgment by default. Action by Attorney General(a) Any act of doing an insurance business, as set forth in subsection (a) of section 38a-271, by any unauthorized person or insurer is equivalent to and shall constitute an irrevocable appointment by such person or insurer, binding upon him, his executor, administrator or personal representative, or successor in interest if a corporation, of the Secretary of the State to be the true and lawful attorney of such person or insurer upon whom may be served all legal process in any action or proceeding in any court by the commissioner or by the state and upon whom may be served any notice, order, pleading or process in any proceeding before the commissioner and which arises out of doing an insurance business in this state by such person or insurer. Any such act of doing an insurance business by any unauthorized person or insurer shall be signification of its agreement that any such legal process in such court action or proceeding and any such notice, order, pleading or process in such administrative proceeding before the commissioner so served shall be of the same legal force and validity as personal service of process in this state upon such person or insurer, or upon his executor, administrator or personal representative, or its successor in interest if a corporation.(b) Such service of process in such court action or proceeding or of such notice, order, pleading or process in such administrative proceeding shall be made by leaving two copies thereof in the hands or at the office of the Secretary of the State. A certificate by the Secretary of the State showing such service and attached to the original or third copy of such process presented to him for that purpose shall be sufficient evidence thereof. Service upon the Secretary of the State as such attorney shall be service upon the principal.(c) The Secretary of the State shall forthwith mail one copy of such court process or such notice, order, pleading or process in proceedings before the commissioner to the defendant in such court proceeding or to the person or insurer to whom the notice, order, pleading or process in such administrative proceeding is addressed or directed at its last-known principal place of business and shall keep a record of all process so served on him which shall show the day and hour of service. Such service is sufficient, provided notice of such service and a copy of the court process or the notice, order, pleading or process in such administrative proceeding shall be sent within ten days thereafter by registered or certified mail by the plaintiff or the plaintiff's attorney in the court proceeding or by the commissioner in the administrative proceeding to the defendant in the court proceeding or to the person or insurer to whom the notice, order, pleading or process in such administrative proceeding is addressed or directed at its last-known principal place of business and the defendant's receipt, or the receipt issued by the post office with which the letter is registered or certified, showing the name of the sender of the letter and the name and address of the person or insurer to whom the letter is addressed, and the affidavit of the plaintiff or the plaintiff's attorney in court proceedings or of the commissioner in administrative proceedings, showing compliance herewith shall be filed with the clerk of the court in which such action, suit or proceeding is pending or with the commissioner in administrative proceedings, on or before the date the defendant in the court or administrative proceeding is required to appear or respond thereto, or within such further time as the court or commissioner may allow.(d) No plaintiff or complainant shall be entitled to a judgment or determination by default in any court or administrative proceeding in which court process or a notice, order, pleading or process in proceedings before the commissioner is served under this section until the expiration of forty-five days from the date of filing of the affidavit of compliance.(e) Nothing contained in this section shall limit or abridge the right to serve any process, notice, order, pleading or demand upon any person or insurer in any other manner permitted by law.(f) The Attorney General upon request of the commissioner is authorized to proceed in the courts of this or any other state or in any federal court or agency to enforce an order or decision in any court proceeding or in any administrative proceeding before the commissioner.Conn. Gen. Stat. § 38a-273
Given statutes' repeated references to "any" act or "an act" of doing insurance business, legislature has made clear that one unauthorized act of doing insurance business will satisfy the statutory requirement for the long arm jurisdiction of Insurance Commissioner. 282 C. 505.