N.H. Rev. Stat. Ann. § 514:3

If no personal service has been made on a defendant in an action which may be entered without such service the court, on suggestion thereof, may order the action to be continued and notice of the pendency thereof to be given by publication, by mail in a registered letter, by personal service or otherwise, as they think proper; and, upon satisfactory evidence that the order has been complied with, the notice shall be sufficient.