This is an excellent thread. It would probably help to add some information on how letters are sorted and how mail actually reduces voter fraud and has been used to detect vote fraud in other countries. This is based on my experience with the Royal Mail in the UK. https://twitter.com/doctorow/status/1293222027499732992

Most letter sorting machinery takes a photo of the front and back and then uses that picture to work out which is the front and then tries to read the address

A lot of countries use sorting machinery and software made by Lockheed Martin (which uses missile recognition technology from their air force jets to recognise handwriting!)

Most of these systems work from the bottom up and assign a probability is there a town with that name in that postcode, is there a road with that name in that town, is there a valid name or number for that house on that road etc.

It then assigns a delivery point suffix for that item (like your postcode but down to an individual house) and prints it as a bar code on the envelope (usually yellowish dashes of some kind)

In sophisticated systems it sorts all the mail in the right order for the delivery person - in older systems it just gives all the mail for an individual delivery route to the person doing the delivery

This is more complicated than it sounds as the way you walk, cycle or drive past houses may vary to be most efficient and many road numbering systems are bewildering in their complexity (do you zig zag across, or one side of the road and back along the other etc.)

Different countries also have different rules about where post should be delivered to - many use a boundary at the edge of the property - others require delivery to the front door.

(don't start me on this topic as will have to tell you about the Outward Bound centre in Scotland that was more than a mile from the nearest road - and where Postcomm (now subsumed into Ofcom) required the Royal Mail to deliver to the door!)

What the letter sorting machinery also records is all the names receiving mail at that address - and this is where mail fraud at scale is hard

Mail operators can see that maybe 6 named people receive mail at an address and if suddenly there are 40 applications for a mail ballot at that address - with many of the names not seen before on other mail at that address - then they can be rightly suspicious

Each individual ballot reply envelope can have a unique code applied when it is sent out and those can also be checked on the return leg against where the outbound envelope was seen in the mail system

This can be a useful alert if very large numbers of ballots are appearing to be returned in different parts of the country from where they were delivered

When you look at the rare cases of postal voting fraud in the UK almost all of them have been identified using these methods (in Birmingham and Tower Hamlets - houses that normally had 5 registered names getting post suddenly had 67 registered voters receiving ballots there)

You can never guarantee that you detect all false voting in any system - what you want to prevent is ballot stuffing at scale by any means you can. Postal voting has the technology to do so and has proven to be efficient, effective and secure

Postal voting is also easy - which may be why Donald Trump himself and most of his family use it. Don't let him deprive US citizens of their right to vote by claiming it is a risk to democracy. Fund the USPS. A small award is due to anyone who gets to the end of this thread!