Iowa Admin. Code r. 821-7.2
If a voter registration acknowledgment card or voter identification card issued pursuant to 2017 Iowa Acts, House File 516, section 18, is mailed to the mailing address listed on a voter's registration record and the acknowledgment is returned to the county registrar as undeliverable by the United States Post Office, the county registrar shall leave the voter's status as active or pending, remove the mailing address from the voter's registration record, and mail another registration acknowledgment or voter identification card to the voter's residential address. If the acknowledgment or voter identification card mailed to the voter's residential address is also returned as undeliverable by the United States Post Office, the voter's registration record shall be made inactive, and the voter shall be mailed a notice as required by Iowa Code section 48A.29, subsection 1.
Iowa Admin. Code r. 821-7.2