Ariz. Rev. Stat. § 16-558.01
Not more than twenty-seven days before the election and not fewer than fifteen days before the election, the county recorder or other officer in charge of elections for the special district shall send by nonforwardable mail all official ballots with printed instructions and a return envelope bearing a printed ballot affidavit as described in section 16-547 to each qualified elector entitled to vote in the election. The envelope in which the ballot is mailed shall be clearly marked with the statement required by the postmaster to receive an address correction and notification. The district governing board shall determine whether the voter or the district governing board will pay for the postage for the return of electors' marked ballots. An elector who votes in a special district mail ballot election shall return the elector's marked ballot to the recorder or other officer in charge of the election or to a designated depository site as provided in section 16-411 no later than 7:00 p.m. on the day of the election.
A.R.S. § 16-558.01