The question has come up this year because long ballots in a number of counties require more than a 42-cent stamp.
Spokesman Augustine Ruiz says the Postal Service has agreements with county election officials nationwide to deliver ballots that lack adequate postage. Counties then reimburse the Postal Service for the missing postage.
"The money that’s actually due the post office, the registrar of voters will be writing that bill whatever that total postage due comes to. We want to make sure that everyone’s votes get in and get counted and so that’s why we have the agreement with the registrar of voters."
More than 6.5 million of the state's nearly 17 million registered voters have requested absentee ballots so far. The head of the county registrar's association expects at least 40% of the votes on November Fourth to be cast using mail-in ballots.