Service of process in any action or proceeding shall be valid if served upon any person within this state who, in this state on behalf of the insurer, is:
and a copy of the process is sent within ten days thereafter by registered or certified mail or statutory overnight delivery by the plaintiff or plaintiff's attorney to the defendant at the last known principal place of business of the defendant; and the defendant's receipt, or the receipt issued by the post office with which the letter is registered or certified, showing the name of the sender of the letter and the name and address of the person to whom the letter is addressed and the affidavit of the plaintiff or plaintiff's attorney showing a compliance with the requirements of this Code section are filed with the clerk of the court in which the action is pending on or before the date the defendant is required to appear or within such further time as the court may allow.
OCGA § 33-5-54