Section 58A. Damages shall not be assessed, except by special order of the court, in an action in which payment of the judgment is secured by a motor vehicle liability policy or a motor vehicle liability bond, both as defined in section thirty-four A of chapter ninety, and wherein the defendant has been defaulted for failure to enter an appearance, until the expiration of four days after the plaintiff has given notice of such default to the company issuing or executing such policy or bond, and has filed an affidavit thereof. Such notice may be given by mailing the same, postage prepaid, to the said company or to its agent who issued or executed such policy or bond.