1. As to elections for LOCAL & STATE offices (where no federal elections are on the ballot): What does your STATE CONSTITUTION say? Does it prescribe any particular โmannerโ of voting? โManner of votingโ refers to a requirement of personal presence at the place of voting and to a show of hands, or voice votes, or paper ballots, or voting machines; etc., OR voting by mail or by internet or by telephone, etc. The Laws made by your State Legislature respecting โmanner of votingโ must comply with your State Constitution, or the pretended laws are unconstitutional.
So! For local & state offices where no federal office is on the ballot; the matter is determined solely by your STATE Constitution and the Statutes your STATE Legislature has passed.
2. As to elections for the FEDERAL House of Representatives or Senate: Seeย Article I, ยง4, clause 1, US Constitution: It provides that State Legislatures have the power to prescribe the โTimes, Places, and Mannerโ of holding elections; but that Congress has an oversight power over the โTimeโ and โMannerโ of election laws made by State Legislatures. [Remember, when Art. I, ยง4, cl. 1 was written, the State Legislatures chose the Stateโs Senators to the US Congress โ so the โplaceโ of choosingย the Senatorsย would be wherever the Legislature met.]
I wrote aboutย Art. I, ยง4, clause 1, US Constitution here. Under the subheading, The Dishonest โElections Clauseโ Argument. Please study that.
It appears that Congress has not passed any Laws prohibiting or requiring mail-in voting in federal elections. (If anyone knows anything to the contrary, please let me know.) If Congress has not passed a law prohibiting mail-in voting, then States may permit it (assuming they are sufficiently foolish to do so). Congress does have the constitutional authority to prohibit mail-in voting in federal elections [and to continue to permit absentee ballots for members of the Military, diplomatic corps, Missionaries, etc.]
3. And remember: The 12thย Amendment sets forth the totally different & separate procedures for electing President & Vice-President. We have ignored the 12thย Amendment for a long timeโฆ