Iowa Code § 461B.4: Manner of service.

Plaintiff in any such action shall cause the original notice of suit to be served as follows:

1. By filing a copy of said original notice of suit with said secretary of state, together with a fee of four dollars, and

2. By mailing to the defendant, and to each of the defendants if more than one, within ten days after said filing with the secretary of state, by restricted certified mail addressed to the defendant at the defendant’s last known residence or place of abode, a notification of the said filing with the secretary of state.