Ariz. Rev. Stat. § 16-509
The board of supervisors, city or town clerk or governing body of a special district shall deliver, by mail or other reliable method, to each voting precinct or to the inspector of each election board as determined by the officer in charge of elections one package containing the required number of ballots, at least forty-eight hours before the hour for opening the polls on election day, unless prevented by some unavoidable delay or accident which shall be established by affidavit of election officers or bearers of ballots. The official ballots shall be sent in sealed packages with marks on the outside of the package clearly designating the polling place for which they are intended and the number of ballots enclosed. Upon delivery of the package to him, the inspector shall return receipts therefor to the person from whom received.
A.R.S. § 16-509