I doubt that 50% of the voting populace will vote by mail and ballots are not universal(automatically) sent out in every state. Your numbers are way off because again you use no link to support your projection that is illusionary at best.
Michigan is one of 12 states automatically sending absentee ballot applications to registered voters.
www.forbes.com
Are ballot application ballots?
No unsolicited ballots are going to be fraudulent and cause chaos and millions of votes will not count because they won’t be counted in time
Each state has rules and protocols for sending ballot applications, receiving and responding to those requests, opening, sorting and counting the mail in ballots.
Will there be confusion? Absolutely. I cite the Iowa caucus results last year. But the Trump campaign position that mail in voting is fraudulent is not born out by facts.
It is massively necessary every American cast a vote this year. And every vote must count. Timeframes are established. And a landslide result is tougher to protest than a razor thin result like Florida 2000.