215 ILCS 5/1017

For the purpose of this Article, an insurance-support organization transacting business outside this State which has an effect on a person residing in this State shall be deemed to have appointed the Director to accept service of process on its behalf, provided the Director causes a copy of such service to be mailed forthwith by registered mail to the insurance-support organization at its last known principal place of business. The return postcard receipt for such mailing shall be sufficient proof that the same was properly mailed by the Director.