Massachusetts General Laws Part III. Courts, Judicial Officers and Proceedings in Civil Cases (Ch. 211-262) Ch. 240, § 10

After all the defendants have been served with process or notified as provided in section seven and after the appointment of a guardian ad litem or next friend, if such appointment has been made, the court may proceed as though all defendants had been actually served with process. Such action shall be a proceeding in rem against the land, and a judgment establishing or declaring the validity, nature or extent of the plaintiff's title may be entered, and shall operate directly on the land and have the force of a release made by or on behalf of all defendants of all claims inconsistent with the title established or declared thereby. This and the four preceding sections shall not prevent the court from also exercising jurisdiction in personam against defendants actually served with process who are personally amenable to its judgments.