R.I. Gen. Laws § 28-35-15: Service on parties outside state.

In case an interested party is located out of the state, and has no post office address within this state, a copy of the petition and copies of all notices shall be filed by the petitioner in the office of the insurance commissioner and shall also be sent by registered or certified mail to the last known post office address of that party. This filing and mailing shall constitute sufficient service, with the same force and effect as if served upon a party located within the state.