that and it would help if you could put an actual person with each mail in ballots. There is no way to check and make sure any of them were real or if they are the actual ones filled out and signed by the real voter and not swapped.mail in ballots should of never happened. Too many factors makes it easy for a "politically powerful" individual to rig said election and leaves doubt in alot of people's minds.
FIrst they (evelopes) are (should be? (based on criteria in the EU)) printed on special paper, that doesnt allow them to be reprinted or forged easily. Second, postal system would notice. Third Electoral offices would notice -- if there is a gross difference in count.
Second, they are sent to 'known home addresses'. That are registered as 'specific people live there'. So any fraud attempt that could 'scale' would have to target the post office, and not individual homes. In my country (EU) you also sign the envelopes, once sealed so that can be compare to a signature from you on record. (That said, graphology is not a science.)
You suggest to replace 'do people have a registered home address' with 'do people have a registered ID'. So how much does that help in your mind?
Third: You make double voting a crime, so people are less likely to fill out 'grannies vote' for them, because granny can go to the police. Also you make them feel bad, because - wtf are you doing. Meaning, there will be individual cases - but thats also not an issue at scale.
Fourth: None of this is especially suitable for 'targeted' voter fraud (meaning, isolating one parties votes and replacing them with another parties votes). So in the end you'd have to 'burn' _all_ vote in a district to engage in any substantial fraud? Also if youd do that - and overdo it with 'stuffing votes' from one party, this will show up in 'statistical likelyhood' checks all over the place - so people will know that you've done it (unless you are super lucky - and only stuff the amount thats statistically probable - while throwing away a bunch of votes you dont know how they've voted in bulk, to replace in bulk).
Fifth: Then the Trump campaign still claims, that bags with thousands of votes showed up at electoral offices out of the blue - meaning, if you can ensure that - why the hell do you bother with manipulating the vote per mail system? Or the other way around - if the Trump campaign cant even prevent that from happening (in their dreams, btw) - why the hell bother tampering with mail votes?
Summery: In his final speech before the Capitol riots, Trump used 100 different potential reasons of how the electoral system could be tempered with as 'proof' - instead of 'having proof', and didnt especially focus on mail in voting (in fact - none of the accusations made in the end focused much on mail voting at all) - so why do you?
Also - Grandpa gets to vote, when he is white, but the black family accross the street isnt allowed to? (Black people less often have voter ID.) Because thats apparently what Trump signaled to his fans all along...
see:
https://www.npr.org/sections/codesw.../the-racial-history-of-the-grandfather-clause
And if you want to pull the 'illegals voting' excuse for the last one - how many illegals do you know with state registered home addresses?