The county auditor shall transmit the appropriate ballots, as promptly as possible, to an absent voter whose application has been recorded under section 203B.19. If the county auditor determines that a voter is not eligible to vote at the primary but will be eligible to vote at the general election, only general election ballots shall be transmitted. Only one set of ballots shall be transmitted to any applicant for any election, except that the county auditor may transmit a replacement ballot to a voter whose ballot has been spoiled or lost in transit or whose mailing address has changed after the date on which the original application was submitted as confirmed by the county auditor. Ballots to be sent outside the United States shall be given priority in transmission. A county auditor may make use of any special service provided by the United States government for the transmission of voting materials under sections 203B.16 to 203B.27.