Snopes has a new article up, complete with video by a postal inspector, that helps support this point. While it is not illegal to send cash through the mail, the postal inspector who has busted postal employees for stealing cash from the mail says you should never send cash through the mail. He cites one case where there was only a small handful of complaints but the postal employee had stolen over hundred cards with cash in them.
See the video near the bottom of this link:
100% vote by mail) showed that one half one percent of people
specifically reported that their vote or votes changed as a result of
pressure from someone nearby when they were voting. This is the
clearest possible evidence of 1/2 of one percent rate of election
fraud. THe problem will only get worse as more people catch on to the
problem and as the system spreads to jurisdictions with more of a
history of political shenanigans like Florida and Ohio.
changed through pressure and intimidation, is nothing less than the
complete privatization of what is supposed to be a public process, and
then ballots sit around for a long time for things to happen to them
like getting "lost" altered, or damaged.
If you like sending cash through the mail, you'll love vote by mail.