The risk of fraud is only one concern being addressed. This system could prevent several possible problems at once.
The biggest improvement is tracking and accountability. Both the outgoing ballot envelope and the return envelope would have unique barcodes, giving election officials much better information about where each ballot is in the system and whether it was delivered or returned.
It would make the process operate more like traditional absentee voting in terms of identifying and tracking the ballots being mailed. States would decide who is eligible to vote and to receive a mailed ballot, and they would have to identify those voters and associate the ballot envelopes with them.
That also addresses the scenario I've talked about the most, which is a large number of ballots being lost or mishandled at one time. With individual tracking, officials would be much better able to determine which voters were affected and allow replacement ballots to be sent to the right people, possibly without the voter even being aware there had been a problem.
The intent is for this to become a nationwide USPS requirement for federal elections using mailed ballots, so that all states using the Postal Service would be operating under the same basic tracking requirements.
Like I've said repeatedly, about a month before the 2020 election I read how the expanded mail-in ballot system was going to work due to COVID and saw the makings of a calamity. There were too many potential bottlenecks and way too much human handling without adequate tracking and accountability to ensure valid ballots got where they were supposed to go to be counted.
One of the two injunctions has already been lifted by the US Supreme Court. The USPS rule is still blocked by the remaining injunction, and we're waiting to see whether that one is lifted as well.
Hopefully this solution will get a chance to be used.
(did I get the details correct? Someone correct me if I didn't)
That moment when you can't make up your mind if you are for or against protectionism because Trump did something.