In Washington State we get mailed ballots, which we fill in and mail in.
But the ballots are not even printed on security paper. They don't have a serial number on them, either.
But the ballots are not even printed on security paper. They don't have a serial number on them, either.
It is then slipped into a security sleeve to make it harder to read within the envelope.
The envelope is sealed and signed by the citizen.
Security is provided by the envelope which is the attestation that the citizen cast their ballot. Offhand, the county voting office is likely required to retain the ballot as part of the state/federal records. I haven't checked but that or a centralized ballot repository are the only things that make sense.
Hence "stuffing" in more ballots cannot be detected.
Printing the ballots on security paper will not eliminate this risk, but it will make it much harder.
I don't know if there is an auditable "chain of custody" of ballots from mailbox to the counting center. The fraud here would be "losing" ballots that are from precincts that tilt significantly in one direction or another.
In other cases, people get money/bag of potatoes for a photo of their correctly filled ballot.
The whole envelope opening and ballot counting process is recorded and streamed live from multiple angles.
https://kingcounty.gov/en/dept/elections/about-us/security-a...
Alas, the signature must reasonably match one on file (from somewhere ... presumably a state ID) or the ballot may be rejected. Since human signatures can vary wildly for reasons, this non-deterministic feature requires a human guess for -each- ballot. No mechanism to dispute that decision.