The American Civil Liberties Union and ACLU of Georgia filed a federal lawsuit April 8, 2020, on behalf of Black Voters Matter challenging the constitutionality of requiring voters to buy postage stamps when submitting mail-in absentee ballots and mailing in absentee ballot applications. This is tantamount to a poll tax.
https://www.aclu.org/cases/black-voters-matter-v-raffensperger