I wish all the vote-by-mail-is-secure shouters knew something about cybersecurity.
1) A chain is only as strong as its weakest link
2) Never consider a system "secure"
3) Always look for exploits, test-replicate and eliminate them
4) Practice continuous vigilence and awareness
5) Use data and statistical anomolies as signals
To me, in CA and WA and likely other vote-by-mail states, there is HUGE exploit window with "vote-by-attestation," and we do not even know the extent of its use, because the Secretaries of State do not track or report the number of ballots submitted via witness attestation.